JP2017201635A - Compact mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mass spectrometer that is compact and portable.SOLUTION: A mass spectrometer 100 is constituted of: a replaceable module 148; and a support base 140 which detachably houses the module. The module has an ion source 102, an ion trap 104, and a detector 118. A pressure adjustment subsystem 120, a voltage source 106, and a controller 108 are attached to the support base. The pressure subsystem is equipped with a small-sized mechanical pump, and can maintain an internal gas pressure within a range from 100 mTorr to 100 Torr. When the ion trap is contaminated or the module is in a failure by use of the mass spectrometer, the spectrometer can be quickly restored by replacing the module with a new one. The contaminated module can be recycled.SELECTED DRAWING: Figure 1E

Description

  The present disclosure relates to the identification of substances using mass spectrometry.

  Mass spectrometers are widely used to detect chemical substances. In a typical mass spectrometer, molecules or particles are excited or ionized, and these excited species often break down to form smaller mass ions or react with other species to form other characteristic ions. To do. This ion formation pattern can be interpreted by the system operator to infer the identity of the compound.

  In general, in a first aspect, the present disclosure provides a mass spectrometer that includes an ion source, an ion trap, an ion detector, and a gas pressure regulation subsystem, wherein during operation of the mass spectrometer, the gas A pressure regulation system is configured to maintain a gas pressure between 100 millitorr and 100 torr in at least two of the ion source, the ion trap, and the ion detector, the ion detector comprising the ion source Is generated in accordance with the mass-to-charge ratio of the ions.

  Embodiments of the mass spectrometer can include one or more of the following features.

  In operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 millitorr and 100 torr in the ion trap and the ion detector. In operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion source and the ion trap. In operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion source and the ion detector. In operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 millitorr and 100 torr in the ion source, the ion trap, and the ion detector.

  The ion source can include a glow discharge ionization source. The ion source can include a capacitor discharge ionization source. The ion source can include a dielectric barrier discharge ionization source.

  The gas pressure regulation system may include a gas pump configured to control the gas pressure in the at least two of the ion source, the ion trap, and the ion detector. The mass spectrometer may include a controller that operates the gas pump to control the gas pressure in the at least two of the ion source, the ion trap, and the ion detector. The gas pump may include a scroll pump.

  In operation, the gas pressure regulation system can be configured to maintain a gas pressure between 500 millitorr and 10 torr in the at least two of the ion source, the ion trap, and the ion detector. In operation, the gas pressure regulation system can be configured to maintain a gas pressure that is less than 10 torr in difference between at least two of the ion source, the ion trap, and the ion detector. In operation, the gas pressure regulation system can be configured to maintain a gas pressure that is less than 10 Torr in the ion source, the ion trap, and the ion detector. In operation, the gas pressure regulation system can be configured to maintain the same gas pressure in at least two of the ion source, the ion trap, and the ion detector. In operation, the gas pressure regulation system can be configured to maintain the same gas pressure in the ion source, the ion trap, and the ion detector.

  The mass spectrometer is a gas path, a gas path connected to the ion source, the ion trap, and the ion detector, and a gas inlet connected to the gas path, and in operation, Gas particles to be analyzed are introduced into the gas path through the gas inlet, and the pressure of the gas particles to be analyzed in the gas path is between 100 mTorr and 100 Torr. Gas inlets. The gas inlet may be configured such that, during operation, a mixture of gas particles including the gas particles to be analyzed and atmospheric gas particles is drawn into the gas inlet, and the gas particle mixture is placed in the gas path. It is not filtered to remove atmospheric gas particles before being introduced.

  The mass spectrometer further includes a sample gas inlet connected to the gas path and a buffer gas inlet connected to the gas path, wherein the gas particles to be analyzed are: Introduced into the gas path through a sample gas inlet; buffer gas particles are introduced into the gas path through the buffer gas inlet; and the gas particles to be analyzed and the buffer in the gas path The sample gas inlet and the buffer gas inlet are configured so that the combined pressure with the gas particles is between 100 mTorr and 100 Torr. The buffer gas particles may include nitrogen molecules and / or noble gas molecules.

  The ion source and the ion trap can be enclosed in a housing that includes a first plurality of electrodes, and the mass spectrometer is configured to releasably engage the first plurality of electrodes. The apparatus further includes a support base having a plurality of electrodes, and the housing can be repeatedly connected to and disconnected from the support base. The mass spectrometer may include an attachment mechanism configured to secure the housing to the support base when the first plurality of electrodes are engaged with the second plurality of electrodes. The attachment mechanism includes at least one of a clamp and a cam.

  The first plurality of electrodes can include a pin, and the second plurality of electrodes can include a socket configured to receive the pin.

  The ion detector can be enclosed within the housing. The gas pressure regulation system can include a pump, and the pump can be enclosed within the housing.

  The support base includes a voltage source coupled to the second plurality of electrodes and a controller connected to the voltage source, the controller including the ion source when the housing is connected to the support base. And the ion trap. In operation, the controller determines the gas pressure in the at least one of the ion source, the ion trap, and the ion detector, and controls the gas pressure by operating the gas pressure adjustment system. Can be configured.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In another aspect, the present disclosure provides for generating a gas pressure between 100 millitorr and 100 torr in at least two of a mass spectrometer ion source, an ion trap, and an ion detector; Detecting the ion according to the mass to charge ratio of the ion.

  Embodiments of the method can include one or more of the following features.

  The method can include maintaining a gas pressure between 100 mTorr and 100 Torr in the ion trap and the ion detector. The method can include maintaining a gas pressure between 100 mTorr and 100 Torr in the ion source and the ion trap. The method can include maintaining a gas pressure between 100 mTorr and 100 Torr in the ion source and the ion detector. The method can include maintaining a gas pressure between 100 mTorr and 100 Torr in the ion source, the ion trap, and the ion detector. The method can include maintaining a gas pressure between 500 mTorr and 10 Torr in the at least two of the ion source, the ion trap, and the ion detector. The method may include maintaining a gas pressure that is less than 10 Torr in at least two of the ion source, the ion trap, and the ion detector. The method can include maintaining a gas pressure of less than 10 Torr in the ion source, the ion trap, and the ion detector. The method may further include maintaining the same gas pressure in at least two of the ion source, the ion trap, and the ion detector. The method may further include maintaining the same gas pressure in the ion source, the ion trap, and the ion detector.

  The method includes introducing gas particles to be analyzed through a gas inlet into a gas path connecting the ion source, the ion trap, and the ion detector, the gas path being Wherein the pressure of the gas particles to be analyzed is between 100 mTorr and 100 Torr. The method may include introducing a mixture of gas particles through a gas inlet into a gas path connecting the ion source, the ion trap, and the ion detector, the gas particles The mixture of gas particles to be analyzed and atmospheric gas particles are not filtered to remove atmospheric gas particles before they are introduced into the gas path.

  The method includes introducing gas particles to be analyzed via a sample gas inlet into a gas path connecting the ion source, the ion trap, and the ion detector; and buffer gas particles Introducing into the gas path via a buffer gas inlet, the combined pressure of the gas particles to be analyzed and the buffer gas particles in the gas path being between 100 mTorr and 100 Torr. It is. The buffer gas particles may include nitrogen molecules and / or noble gas molecules.

  Embodiments of the method can include any other features disclosed herein, in any combination, as appropriate.

  In a further aspect, the present disclosure provides a mass spectrometer including a support base featuring a first plurality of electrodes and a pluggable module featuring a second plurality of electrodes, the pluggable module comprising: The second plurality of electrodes are configured to be releasably connected to the support base by engaging the second plurality of electrodes with the first plurality of electrodes, and the pluggable module includes an ion trap connected to a gas path. Including.

  Embodiments of the mass spectrometer can include one or more of the following features.

  The pluggable module can include an ion trap connected to the gas path. The second plurality of electrodes can include a pin, and the first plurality of electrodes can include a socket configured to receive the pin.

  The support base includes a first mounting mechanism, and the pluggable module includes a second mounting mechanism configured to engage the first mounting mechanism.

  The first and second attachment mechanisms can be configured such that the pluggable module is releasably connected to the support base in only one orientation. One of the first and second attachment mechanisms can include an asymmetric extending member, and the other of the first and second attachment mechanisms includes a recess configured to accommodate the extending member. it can. At least one of the first and second attachment mechanisms may include a soft sealing member. At least one of the first and second attachment mechanisms may include at least one of a clamp and a cam.

  The mass spectrometer can include a sample gas inlet connected to the gas path. The mass spectrometer may include an ion detector attached to the support base. The pluggable module can include an ion detector connected to the gas path. The ion detector can be disposed on the support base such that when the pluggable module is attached to the support base, the ion detector is connected to the gas path.

  The mass spectrometer may include a pump attached to the support base. The pluggable module can include a pump connected to the gas path. The pump may be disposed on the support base such that when the pluggable module is attached to the support base, the pump is connected to the gas path. The pump may include a scroll pump.

  The ion source may include a glow discharge ionization source and / or a capacitor discharge ionization source.

  The mass spectrometer may include an ion detector connected to the gas path and a controller attached to the support base and connected to the ion trap. During operation of the mass spectrometer, the controller uses the detector to detect ions generated by the ion source, identifies information related to the identity of the detected ions, and uses an output interface Can be configured to display that information.

  The mass spectrometer may include a pump connected to the gas path and configured to maintain the pressure of the gas particles in the range of 100 millitorr to 100 torr. The mass spectrometer may include a controller connected to the ion trap and the pump, and during operation of the mass spectrometer, the controller determines a pressure of gas particles in the gas path, and the gas particles The pump can be configured to operate to maintain the pressure in the range of 100 millitorr to 100 torr.

  The pump can be configured to maintain the pressure of the gas particles in the range of 100 millitorr to 100 torr.

  The mass spectrometer may include an enclosure that surrounds the support base and the pluggable module, the enclosure including an opening disposed adjacent to the pluggable module, the mass spectrometer The user can connect and disconnect the pluggable module to the support base through the opening. The mass spectrometer may include a cover member that closes the opening of the enclosure when placed. The cover member may include a retractable door. The cover member may include a lid that is completely removable from the enclosure.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In another aspect, the present disclosure provides a mass spectrometer system that includes any of the mass spectrometers disclosed herein, the mass spectrometer including a first pluggable module and one or more Each of the additional pluggable modules includes an ion trap and a third plurality of electrodes, the additional pluggable module including the third plurality of electrodes. It is configured to releasably connect to the support base by engaging with the first plurality of electrodes.

  Embodiments of the system can include one or more of the following features.

  At least one of the additional plug-in modules can include an ion trap that is substantially similar to the ion trap of the first pluggable module.

  The first pluggable module can include an ion source, and at least one of the additional pluggable modules can include a different ion source than the ion source of the first pluggable module. it can. For example, the ion source of the first pluggable module can include a glow discharge ionization source, and at least one of the additional pluggable modules is an ionization source (e.g., different from the glow discharge ionization source). Electrospray ionization source, dielectric barrier discharge ionization source, and / or capacitor discharge ionization source).

  At least one of the additional plug-in modules can include an ion trap that is different from the ion trap of the first pluggable module. The diameter of the ion trap of the first plug-in module may be different from the diameter of at least one ion trap of the additional pluggable module. Alternatively or additionally, the cross-sectional shape of the ion trap of the first plug-in module may be different from the cross-sectional shape of at least one ion trap of the additional pluggable module.

  The first pluggable module can include an ion detector, each of the additional pluggable modules can include an ion detector, and the ion detector of the first pluggable module. May be different from at least one of the ion detectors of the additional pluggable module.

  At least one surface of the first pluggable module can include a first coating, and at least one surface of the additional pluggable module has a second coating that is different from the first coating. Can be included.

  Embodiments of the system can include any other features disclosed herein, in any combination, as appropriate.

  In a further aspect, the present disclosure is a mass spectrometer comprising a support base, an ion source attached to the support base, an ion trap attached to the support base, and an ion detection attached to the support base. And a power source attached to the support base, the power source being electrically connected to the ion source, the ion trap, and the ion detector via the support base. Providing and during operation of the mass spectrometer, the power source is configured to supply power to the ion source, the ion trap, and the ion detector.

  Embodiments of the mass spectrometer can include one or more of the following features.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  The mass spectrometer may include a gas pressure regulation system attached to the support base and electrically connected to the power supply through the support base, and during operation of the mass spectrometer, the power supply is Power is configured to be supplied to the gas pressure adjustment system. The mass spectrometer is a controller attached to the support base, and is electrically connected to the ion source, the ion trap, the ion detector, and the gas pressure adjustment system via the support base. A connected controller can be included. The ion source, the ion trap, and the ion detector can be connected to a gas path, and during operation of the mass spectrometer, the gas pressure regulation system can adjust a gas pressure in the gas path from 100 millitorr to 100 torr. (Eg, in the range of 500 mTorr to 10 Torr). The gas pressure adjustment system may include a scroll pump.

  The support base may include a printed circuit board.

  The mass spectrometer may include a gas inlet connected to the gas path, and the gas inlet includes a gas containing the analyzed gas particles and atmospheric gas particles during operation of the mass spectrometer. A mixture of particles is configured to be drawn into the gas inlet through the gas inlet, and the gas particle mixture is introduced into the gas path without filtering the atmospheric gas particles. The gas inlet may include a valve electrically connected to the controller, and when the mass spectrometer is in operation, the controller removes the gas particle mixture for at least 30 seconds. It can comprise so that it may introduce in the said gas path via.

  During operation of the mass spectrometer, the controller is configured to detect ions generated by the ion source using the ion detector and adjust a duty cycle of the ion source based on the detected ions. it can. The controller can be configured to adjust the duty cycle of the ion source by adjusting a time interval at which the ion source generates ions. The controller can be configured to adjust the duty cycle of the ion source by adjusting at least one of the period and magnitude of the potential applied to the electrode of the ion source.

  During operation of the mass spectrometer, the controller can be configured to identify information related to the identity of the detected ions and display the information using an output interface.

  The ion source may include a glow discharge ionization source and / or a dielectric barrier discharge ionization source.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In another aspect, the present disclosure is a mass spectrometer comprising an ion source, an ion trap, a detector connected to a gas path; a gas inlet connected to the gas path and having a valve; Providing a mass spectrometer comprising: a pressure regulating system configured to control a gas pressure in the gas path; and a controller connected to the valve, the ion source, the ion trap, and the detector; During operation of the mass spectrometer, the pressure regulation system is configured to maintain a gas pressure in the gas path that is greater than 100 millitorr, and the controller includes: (a) a mixture of gas particles in the gas path. The valve is operated so that the mixture includes gas particles to be analyzed and atmospheric gas particles, and the mixture of gas particles comprises Introduced into the gas path without error, the controller (b) activates the ion source to generate ions from the analyzed gas particles, and the controller (c) activates the detector. Then, the ions are detected according to the mass-to-charge ratio of the ions.

  Embodiments of the mass spectrometer can include one or more of the following features.

  The atmospheric gas particles may include at least one of nitrogen molecules and oxygen molecules. The pressure regulation system can be configured to maintain a gas pressure above 500 millitorr (eg, 1 torr) in the gas path. The controller may be configured to actuate the valve to continuously introduce the gas particle mixture into the gas path for at least 10 seconds (at least 30 seconds, at least 1 minute, at least 2 minutes).

  The mass spectrometer includes a housing surrounding the ion source and the ion trap, the housing including a first plurality of electrodes connected to the ion source and the ion trap, and the first plurality of electrodes. And a support base with a second plurality of electrodes configured to mate, wherein the housing forms a pluggable module configured to releasably connect to the support base. The controller is connectable to the support base.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  In operation, the controller can be configured to adjust the duty cycle of the ion source based on the detected ions. For example, the controller may generate ions from the analyzed gas particles for a continuous period of 10 seconds or longer (e.g., for a continuous period of 30 seconds or longer, for a continuous period of 1 minute or longer, for a continuous period of 2 minutes or longer) As such, the ion source can be configured to be adjusted.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In a further aspect, the present disclosure includes: introducing a mixture of gas particles into a gas path of a mass spectrometer, the gas particle mixture including gas particles to be analyzed and atmospheric gas particles, wherein the gas particles The atmospheric gas particles are introduced without filtration; maintaining a gas pressure above 100 millitorr in the gas path; using an ion source connected to the gas path Generating ions from the gas particles to be analyzed; and detecting the ions according to a mass-to-charge ratio of the ions using a detector connected to the gas path.

  Embodiments of the method can include one or more of the following features.

  The atmospheric gas particles may include at least one of nitrogen molecules and oxygen molecules.

  The method can include maintaining a gas pressure in the gas path of greater than 500 millitorr (eg, 1 torr). The method can include continuously introducing the mixture of gas particles into the gas path for at least 10 seconds (over at least 30 seconds, over at least 2 minutes). The method adjusts the ion source such that ions are generated from the analyzed gas particles for a continuous period of 10 seconds or longer (e.g., for a continuous period of 30 seconds or longer, for a continuous period of 2 minutes or longer). Steps may be included.

  Embodiments of the method can include any other features disclosed herein, in any combination, as appropriate.

  In another aspect, the present disclosure provides an ion source, an ion trap, an ion detector, and a single mechanical pump configured to control gas pressure in the ion source, the ion trap, and the ion detector And a controller connected to the ion source, the ion trap, and the ion detector, wherein the single mechanical pump controls the gas pressure. In operation, the controller operates the ion detector to detect ions generated by the ion source according to the mass-to-charge ratio of the ions. It is configured to

  Embodiments of the mass spectrometer can include one or more of the following features.

  The single mechanical pump may include a scroll pump. The single mechanical pump can operate at less than 4000 cycles per minute to control the gas pressure.

  During operation of the mass spectrometer, the single mechanical pump can maintain a gas pressure between 100 millitorr and 100 torr in at least two of the ion source, the ion trap, and the ion detector. During operation of the mass spectrometer, the single mechanical pump can maintain a gas pressure between 500 mTorr and 10 Torr in at least two of the ion source, the ion trap, and the ion detector. During operation of the mass spectrometer, the single mechanical pump can maintain a common gas pressure in at least two of the ion source, the ion trap, and the ion detector. During operation of the mass spectrometer, the single mechanical pump can maintain a gas pressure with a difference of 10 Torr or less in the ion source, the ion trap, and the ion detector.

  The controller can be connected to the pump, and the controller can be configured to control the number of pumps during operation of the mass spectrometer. During operation of the mass spectrometer, the controller can be configured to detect ions generated by the ion source using the ion detector and adjust the number of pumps based on the detected ions.

  The ion source may include a glow discharge ionization source, a dielectric barrier discharge ionization source, and / or a capacitor discharge ionization source.

  The mass spectrometer is configured to engage the first plurality of electrodes, and a housing that includes the first plurality of electrodes that surround the ion source and the ion trap and is connected to the ion source and the ion trap. And a support base with a second plurality of electrodes, wherein the housing is a pluggable module configured to releasably connect to the support base. The housing can surround the pump. The controller can be attached to the support base. The support base may include a printed circuit board. The electrical processor can be electrically connected to the ion source and the ion trap via the support base.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer is less than 4.5 kg.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In a further aspect, the present disclosure uses a single mechanical pump to control gas pressure in an ion source, ion trap, and ion detector of a mass spectrometer, and includes ions generated by the ion source. Using the ion detector to detect according to the mass to charge ratio of ions, and using the single mechanical pump to control gas pressure controls the gas pressure. Therefore, the pump is operated at a frequency of less than 6000 cycles per minute.

  Embodiments of the method can include one or more of the following features.

  The method can include operating the pump at a rate of less than 4000 cycles per minute to control the gas pressure. The method maintains a gas pressure between 100 mTorr and 100 Torr (eg, between 500 mTorr and 10 Torr) in at least two of the ion source, the ion trap, and the ion detector. Can be included.

  The method can include maintaining a common gas pressure in at least two of the ion source, the ion trap, and the ion detector. The method can include maintaining a gas pressure of less than 10 Torr in the ion source, the ion trap, and the ion detector.

  The method can include adjusting the number of times of the pump based on the detected ions (eg, based on the abundance of the detected ions).

  Embodiments of the method can include any other features disclosed herein, in any combination, as appropriate.

  In another aspect, the present disclosure is a mass spectrometer comprising an ion source, an ion trap, an ion detector, a user interface, the ion source, the ion trap, the ion detector, and the user interface. A mass spectrometer comprising: a controller coupled to the controller, wherein during operation of the mass spectrometer, the controller detects ions generated by the ion source using the ion detector; A chemical name associated with the selected ion and configured to display the chemical name on the user interface, the user interface being activated by a user after the chemical name is displayed to the controller Control means for displaying the spectrum of the detected ions on the user interface; No.

  Embodiments of the mass spectrometer can include one or more of the following features.

  Displaying the spectrum of the detected ions includes displaying the abundance of the detected ions as a function of the mass to charge ratio of the ions. The control means may include at least one of a button, a switch, and a touch screen display area. During operation of the mass spectrometer, the controller can be further configured to display a hazard associated with the detected ions on the user interface.

  The ion source may be at least one of a glow discharge ionization source, a capacitor discharge ionization source, and a dielectric barrier discharge ionization source.

  During operation of the mass spectrometer, the controller can be configured so that the spectrum of the detected ions is not displayed unless the control means is activated.

  The ion detector can include a Faraday detector.

  The mass spectrometer can include a pressure regulation system, and during operation of the mass spectrometer, the pressure regulation system is between 100 millitorr and 100 torr in the ion trap and the ion detector (eg, 500 It is configured to maintain gas pressure (between millitorr and 10 torr).

  The pressure regulation system may include a scroll pump.

  The mass spectrometer includes a pluggable module comprising the ion source, the ion trap, the ion source and a first plurality of electrodes connected to the ion trap, a voltage source and the first plurality of electrodes. And a support base with a second plurality of electrodes configured to engage, wherein the pluggable module is configured to releasably connect to the support base.

  The pluggable module can include the ion detector. The pluggable module can include a pressure regulation system.

  The mass spectrometer is a housing that surrounds the pluggable module and the support base, and includes an opening disposed adjacent to the pluggable module and inserting the pluggable module into the opening. A housing configured to be releasably connectable to the support base may be included.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In a further aspect, the present disclosure is a mass spectrometer comprising an ion source, an ion trap, an ion detector, a user interface, the ion source, the ion trap, the ion detector, and the user interface. A mass spectrometer including a connected controller, wherein the user interface includes control means that allows a user of the mass spectrometer to operate in any of at least two states, and when the mass spectrometer is in operation, the controller Detects the ions generated by the ion source using the ion detector, identifies the chemical name associated with the detected ions, and when the control means is activated to the first state, When the chemical name is displayed on the user interface and the control means is activated to the second state, the user interface It is configured to display the spectrum of the detected ions on the face.

  Embodiments of the mass spectrometer can include one or more of the following features.

  When the controller is activated to the second state, the controller can be further configured to display the chemical name on the user interface. Displaying the spectrum of the detected ions can include displaying the abundance of the detected ions as a function of the mass to charge ratio of the ions. The control means may include at least one of a button, a switch, and a touch screen display area.

  The ion source can be at least one of a glow discharge ionization source, a capacitor discharge ionization source, and / or a dielectric barrier discharge ionization source.

  The mass spectrometer can include a pressure regulation system connected to the controller, and during operation of the mass spectrometer, the pressure regulation system is configured to provide 100 millitorr and 100 torr at the ion trap and the ion detector. It is configured to maintain a gas pressure between (eg, between 500 mTorr and 10 Torr). The pressure regulation system may include a scroll pump.

  The mass spectrometer includes a pluggable module including the ion source, the ion trap, the ion source and a first plurality of electrodes connected to the ion trap, a voltage source, and the first plurality of electrodes. And a support base including a second plurality of electrodes configured to mate, wherein the pluggable module is configured to releasably connect to the support base. The pluggable module can include the ion detector and / or a pressure regulation system.

  The mass spectrometer is a housing that surrounds the pluggable module and the support base, and includes an opening disposed adjacent to the pluggable module and inserting the pluggable module into the opening. A housing configured to be releasably connectable to the support base may be included.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In another aspect, the present disclosure provides a mass spectrometer comprising an ion source, an ion trap, an ion detector, a sample inlet, and a pressure adjustment system, wherein the ion source The ion trap, the ion detector, the sample inlet, and the pressure adjustment system are connected to a gas path, and during operation of the mass spectrometer, gas particles are only passed through the sample inlet. The pressure regulation system is configured to maintain a gas pressure between 100 millitorr and 100 torr in the gas path, and the ion detector is generated from the gas particles by the ion source. It is configured to detect ions according to the mass-to-charge ratio of the ions.

  Embodiments of the mass spectrometer can include one or more of the following features.

  The pressure regulation system can be configured to maintain the gas pressure between 500 millitorr and 10 torr. The pressure regulation system can be configured to maintain the gas pressure above 500 millitorr.

  The ion source may include at least one of a glow discharge ionization source, a capacitor discharge ionization source, and a dielectric barrier discharge ionization source.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  The pressure regulation system may include a scroll pump.

  The sample inlet may be configured such that gas particles introduced into the gas path include gas particles to be analyzed and atmospheric gas particles.

  The mass spectrometer may include a valve connected to the sample inlet and a controller connected to the valve, and when the mass spectrometer is in operation, the controller sends the gas particles to the sample. It can be configured to continuously introduce through the inlet into the gas path for at least 30 seconds (at least 1 minute, at least 2 minutes).

  The mass spectrometer may include a controller connected to the ion source, and during operation of the mass spectrometer, the controller adjusts a potential applied to the ion source so that ions are present in the ion source. Can be generated continuously from the gas particles for at least 30 seconds (at least 1 minute, at least 2 minutes).

  The mass spectrometer includes a pluggable module comprising the ion source, the ion trap, the ion source and a first plurality of electrodes connected to the ion trap, a voltage source and the first plurality of electrodes. And a support base with a second plurality of electrodes configured to engage, wherein the pluggable module is configured to releasably connect to the support base. The pluggable module can include the pressure regulation system.

  The mass spectrometer is a housing that surrounds the pluggable module and the support base, and includes an opening disposed adjacent to the pluggable module and inserting the pluggable module into the opening. A housing configured to be releasably connectable to the support base may be included.

  The pressure regulation system can include a single mechanical pump, and during operation of the mass spectrometer, the single mechanical pump is less than 6000 cycles per minute to maintain the gas pressure in the gas path It is configured to operate at the number of times.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In a further aspect, the present disclosure includes introducing a mixture of gas particles into a gas path of a mass spectrometer via a single gas inlet, the gas particle mixture being analyzed by the gas particles and the atmosphere. Introducing only gas particles, maintaining a gas pressure between 100 mTorr and 100 Torr in the gas path, and mass-to-charge ratio of ions generated from the analyzed gas particles And detecting in accordance with the method.

  Embodiments of the method can include one or more of the following features.

  The method can include maintaining the gas pressure between 500 mTorr and 10 Torr. The method can include maintaining the gas pressure above 500 millitorr.

  The method includes continuously introducing the mixture of gas particles into the gas path via the single gas inlet for at least 30 seconds (for at least 1 minute, for at least 2 minutes). Can do.

  The method adjusts the potential applied to the ion source of the mass spectrometer so that ions are continuously generated from the analyzed gas particles for at least 30 seconds (at least 1 minute, at least 2 minutes). Steps may be included.

  The method can include operating the single mechanical pump at a rate of less than 6000 cycles per minute to maintain the gas pressure in the gas path.

  Embodiments of the method can include any other features disclosed herein, in any combination, as appropriate.

  In another aspect, the present disclosure provides an ion source featuring an exit electrode, the ion source passing through the exit electrode when ions exit the ion source, and an entrance disposed adjacent to the exit electrode Providing a mass spectrometer including an ion trap characterized by an electrode, an ion detector, and a pressure regulation system, wherein the exit electrode includes one or more apertures defining a cross-sectional shape of the exit electrode; The inlet electrode includes one or more apertures that define a cross-sectional shape of the inlet electrode; the cross-sectional shape of the outlet electrode substantially matches the cross-sectional shape of the inlet electrode; In operation, the pressure regulation system is configured to maintain a gas pressure of at least 100 millitorr in the ion trap, and the ion detector is generated by the ion source. And the ions are arranged to detect in accordance with mass-to-charge ratio of the ions.

  Embodiments of the mass spectrometer can include one or more of the following features.

  The ion trap includes one or more ion chambers, the one or more ion chambers defining a cross-sectional shape of the ion trap, the cross-sectional shape of the ion trap being the cross-sectional shape of the inlet electrode. Can substantially match.

  The one or more apertures of the exit electrode may include a number of apertures arranged in a rectangular or square array. The one or more apertures of the exit electrode can include a number of apertures arranged in a hexagonal array. The one or more apertures of the exit electrode may include an aperture with a rectangular cross-sectional shape. The one or more apertures of the exit electrode may include an aperture with a helical cross-sectional shape. The one or more apertures of the exit electrode may include apertures having a serpentine cross-sectional shape. The one or more apertures of the exit electrode may include four apertures (eg, 8 or more apertures, 24 or more apertures, 100 or more apertures). The one or more apertures of the exit electrode can include a plurality of apertures arranged in a serpentine pattern.

  The mass spectrometer may include a voltage source connected to the outlet electrode and the first electrode of the ion source, and a controller connected to the voltage source. During operation of the mass spectrometer, the controller Can be configured to operate the ion source in one of at least two modes by applying different potentials with respect to a common ground potential to the first electrode and the exit electrode. In the first mode of the at least two modes, the controller is configured to apply a potential to the first electrode and the outlet electrode such that the first electrode is a positive potential with respect to the common ground potential. In the second mode of the at least two modes, the controller is configured to apply a potential to the first and second electrodes such that the first electrode has a negative potential with respect to the common ground. it can.

  The mass spectrometer is a user interface with selectable control means, and the controller changes the operating mode of the ion source when the control means is activated during operation of the mass spectrometer. A user interface configured to be included.

  The ion source can include a glow discharge ionization source.

  The mass spectrometer may include a detector connected to the controller, and during operation of the mass spectrometer, the controller uses the ion detector to detect ions generated by the ion source. The potential applied to the first electrode and the outlet electrode may be adjusted based on the detected ions to control a period during which the ion source continuously generates ions. During operation of the mass spectrometer, the ion source can generate ions in a plurality of ionization cycles that define an ion source frequency, each ionization cycle having a first interval during which ions are generated and a second in which no ions are generated. The first and second intervals define a duty cycle, and the controller sets the duty cycle to a value between 1% and 40% (e.g., between 1% and 20%). Value between 1% and 10%).

  During operation of the mass spectrometer, the controller determines when the ion source should be cleaned based on the detected ions and sets the duty cycle of the ion source to 50% and 90%. The ion source can be configured to operate for at least 30 seconds to adjust to a value in between and to clean the ion source.

  The pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr (eg, between 500 mTorr and 10 Torr) in the ion trap.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In a further aspect, the present disclosure provides an ion source, an ion trap, an ion detector, a pressure regulation system, and a voltage source connected to the ion source, the ion trap, the ion detector, and the pressure regulation system. And a controller connected to the ion source, the ion trap, the ion detector, and the voltage source, and during operation of the mass spectrometer, the controller Actuate to generate ions from gas particles, actuate the ion detector to detect ions generated by the ion source, and adjust the resolution of the mass spectrometer based on the detected ions Composed.

  Embodiments of the mass spectrometer can include one or more of the following features.

  The controller can be connected to the pressure regulation system and can be configured to adjust the resolution by operating the pressure regulation system to change a gas pressure in at least one of the ion source and the ion trap. The controller may be configured to adjust the resolution by operating the pressure regulation system to reduce the gas pressure in the at least one of the ion source and the ion trap.

  The controller can be configured to repeatedly apply a potential to the central electrode of the ion trap using the voltage source to eject ions from the ion trap, wherein the repeated application of the potential defines the number of repetitions of the potential. The controller may further be configured to adjust the resolution by changing the number of repetitions of the potential. The controller can be configured to increase the resolution by increasing the repeated application of the potential.

  The controller may be configured to adjust the resolution by changing a maximum amplitude of a potential applied to the central electrode of the ion trap by the voltage source.

  The controller may be configured to adjust the resolution by applying an axial potential difference between the electrodes at the opposite ends of the ion trap using the voltage source and changing the magnitude of the axial potential difference. The controller can be configured to increase the resolution by increasing the magnitude of the axial potential difference.

  The controller can be configured to repeatedly apply a potential difference between the electrodes of the ion source using the voltage source to generate the ions, wherein the repeated application of the potential defines a repetition number of the ion source, and The controller can be further configured to adjust the resolution by changing the number of repetitions of the ion source. The controller can be configured to synchronize the repetition number of the ion source and the repetition number of the potential applied to the central electrode of the ion trap.

  The controller may be configured to repeatedly apply a potential difference between the electrodes of the ion source using the voltage source, the repeated application of the potential defining a repetition period of the ion source, wherein the repetition period is the potential difference. Includes a first time interval applied between the electrodes of the ion source and a second time interval during which the potential difference is not applied between the electrodes of the ion source; the controller further includes the ion source The resolution can be adjusted by adjusting the duty cycle, wherein the duty cycle corresponds to a ratio of the first time interval to the repetition period. The controller can be configured to increase the resolution by decreasing the duty cycle of the ion source.

  The mass spectrometer is a gas path including a gas path to which the ion source, the ion trap, the ion detector, and the pressure adjustment system are connected, and a gas introduction port connected to the gas path. A gas inlet having a valve connected to the controller, and the controller controls the valve to control the valve so that the buffer gas particles are in the buffer gas inlet. The ratio of the gas introduced into the gas path via the gas is adjusted. In order to increase the degree of resolution, the controller can be configured to increase the rate at which buffer gas particles are introduced into the gas path.

  During operation of the mass spectrometer, the controller: repeatedly activates the ion source to generate ions from gas particles, operates the ion detector to detect ions generated by the ion source, and the mass Adjusting the resolution of the analyzer based on the detected ions, and performing these until the resolution of the mass spectrometer reaches a threshold; the resolution of the mass spectrometer is at least equal to the threshold Actuating the ion detector to detect ions generated from the gas particles when the size is reached; ions detected when the resolution of the mass spectrometer is at least as large as the threshold Information on the identity of the gas particles can be identified on the basis of; and the information can be displayed on a user interface. The information may include information relating to the chemical name of the gas particle and / or information relating to the hazard associated with the gas particle and / or information relating to the type of substance to which the gas particle corresponds.

  During operation of the mass spectrometer, the controller may adjust the potential source so that a potential is applied to the central electrode of the ion trap only when the resolution reaches the threshold.

  During operation of the mass spectrometer, the pressure regulation system is between 100 millitorr and 100 torr (e.g., 500 millitorr and 10 torr) in at least two of the ion source, the ion trap, and the ion detector. Can be configured to maintain the gas pressure.

  The mass spectrometer comprises a pluggable module comprising the ion source, the ion trap, the detector, and a first plurality of electrodes connected to the ion source, the ion trap, and the detector; A support base with a second plurality of electrodes configured to releasably engage the first plurality of electrodes, wherein the voltage source and the controller are attached to the support base and are pluggable The module is configured to releasably connect to the support base.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In another aspect, the present disclosure provides for introducing gas particles into an ion source of a mass spectrometer, generating ions from the gas particles, and detecting the ions using a detector of the mass spectrometer. Adjusting the resolution of the mass spectrometer based on the detected ions.

  Embodiments of the method can include one or more of the following features.

  Adjusting the resolution may include changing a gas pressure in at least one of the ion source and the ion trap. The method can include increasing the degree of decomposition by reducing the gas pressure in the at least one of the ion source and the ion trap.

  The method includes the step of repeatedly applying a potential to a central electrode of the trap to eject ions from the ion trap, wherein the repeated application of the potential defines a number of repetitions of the potential; and The controller may further include adjusting the resolution by changing the number of repetitions of the potential. The method can include increasing the resolution by increasing the number of repetitions of the potential. The method may include adjusting the resolution by changing a maximum amplitude of a potential applied to a central electrode of the ion trap.

  The method can include applying an axial potential difference between electrodes at opposite ends of the ion trap and adjusting the resolution by changing the magnitude of the axial potential difference. The method may include increasing the resolution by increasing the magnitude of the axial potential difference.

  The method includes the step of repeatedly applying a potential difference between the electrodes of the ion source to generate the ions, wherein the repetitive application of the potential defines the number of repetitions of the ion source; and Adjusting the degree of resolution by changing the number of repetitions of the source. The controller can be configured to synchronize the number of repetitions of the ion source and the number of repetitions of the potential applied to the central electrode of the ion trap.

  The method includes the step of repeatedly applying a potential difference between the electrodes of the ion source, wherein the repeated application of the potential defines a repetition period of the ion source, wherein the potential difference is determined by the potential difference of the ion source. Applying a first time interval applied between the electrodes and a second time interval in which the potential difference is not applied between the electrodes of the ion source; adjusting a duty cycle of the ion source; Adjusting the degree of resolution thereby, the duty cycle corresponds to a ratio of the first time interval to the repetition period. The method can include reducing the resolution by reducing the duty cycle of the ion source.

  In order to adjust the resolution, the method may include increasing the rate at which buffer gas particles are introduced into the gas path of the mass spectrometer. In order to increase the degree of decomposition, the method can include increasing the rate at which buffer gas particles are introduced into the gas path.

  The method includes: repeatedly operating the ion source to generate ions from gas particles; operating the ion detector to detect ions generated by the ion source; and Adjusting the resolution based on the detected ions, and performing these until the resolution of the mass spectrometer reaches a threshold; the resolution of the mass spectrometer is at least the same as the threshold Activating the ion detector to detect ions generated from the gas particles when the gas analyzer is sized; detected when the resolution of the mass spectrometer is at least as large as the threshold value; Identifying information relating to the identity of the gas particles based on the detected ions; and displaying the information on a user interface. Can. The information may include information relating to the chemical name of the gas particle and / or information relating to the hazard associated with the gas particle and / or information relating to the type of substance to which the gas particle corresponds.

  The method may include applying a potential to the central electrode of the ion trap only when the resolution reaches the threshold value.

  The method maintains a gas pressure between 100 mTorr and 100 Torr (eg, between 500 mTorr and 10 Torr) in at least two of the ion source, the ion trap, and the ion detector. Can be included.

  Embodiments of the method can include any other features disclosed herein, in any combination, as appropriate.

  In a further aspect, the present disclosure provides an ion source, an ion trap, an ion detector, a gas pressure regulation system featuring a single mechanical pump, the ion source, the ion trap, and the ion detector. A mass spectrometer including a connected controller, wherein during operation of the mass spectrometer, the gas pressure regulation subsystem is configured to provide 100 millitorr in at least two of the ion source, the ion trap, and the ion detector. And the controller is configured to operate the ion detector to detect ions generated by the ion source according to the mass-to-charge ratio of the ions. And the single mechanical pump operates at less than 6000 cycles per minute to maintain the gas pressure.

  Embodiments of the mass spectrometer can include one or more of the following features. In operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 millitorr and 100 torr in the ion trap and the ion detector. In operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 mTorr and 100 Torr in the ion source and the ion trap. In operation, the gas pressure regulation system can be configured to maintain a gas pressure between 100 millitorr and 100 torr in the ion source, the ion trap, and the ion detector.

  The mechanical pump may be a scroll pump.

  In operation, the gas pressure regulation system can be configured to maintain a gas pressure that is less than 10 torr in difference between at least two of the ion source, the ion trap, and the ion detector. In operation, the gas pressure regulation system can be configured to maintain a gas pressure that is less than 10 Torr in the ion source, the ion trap, and the ion detector. In operation, the gas pressure regulation system can be configured to maintain the same gas pressure in at least two of the ion source, the ion trap, and the ion detector.

  The mass spectrometer is a gas path including a gas path to which the ion source, the ion trap, the ion detector, and the gas pressure adjustment system are connected, and a gas inlet connected to the gas path. In operation of the mass spectrometer, gas particles to be analyzed are introduced into the gas path through the gas inlet, and the total pressure in the gas path is between 100 mTorr and 100 Torr. And a gas inlet configured as described above. The gas inlet may be configured to draw a mixture of gas particles including the analyzed gas particles and atmospheric gas particles into the gas inlet during operation of the mass spectrometer, and the mixture of gas particles includes: It is not filtered to remove atmospheric gas particles before they are introduced into the gas path.

  The mass spectrometer is a gas path including a gas path to which the ion source, the ion trap, the ion detector, and the gas pressure adjustment system are connected, and a sample gas inlet connected to the gas path. A buffer gas inlet connected to the gas path, and during operation of the mass spectrometer: gas particles to be analyzed are introduced into the gas path via the sample gas inlet; Buffer gas particles are introduced into the gas path through the buffer gas inlet, and the combined pressure of the gas particles to be analyzed and the buffer gas particles in the gas path is between 100 mTorr and 100 Torr. Thus, the sample gas inlet and the buffer gas inlet are configured. The buffer gas particles may include at least one of nitrogen molecules and rare gas molecules.

  The mass spectrometer is releasable to the first plurality of electrodes, the pluggable module comprising the ion source, the ion trap, and the first plurality of electrodes connected to the ion source and the ion trap. A support base with a second plurality of electrodes configured to engage may further be included, wherein the pluggable module is connectable to and detachable from the support base. The mass spectrometer may include an attachment mechanism configured to secure the pluggable module to the support base when the first plurality of electrodes engage the second plurality of electrodes. The first plurality of electrodes can include a pin, and the second plurality of electrodes can include a socket configured to receive the pin.

  The pluggable module can include the ion detector, and the first plurality of electrodes can be connected to the ion detector. The pluggable module can include the mechanical pump.

  The mass spectrometer may include a voltage source, and the voltage source and the controller are attached to the support base and connected to the second plurality of electrodes.

  The support base may include a printed circuit board. The controller may be further connected to the ion source and the ion trap when the pluggable module is connected to the support base.

  The single mechanical pump can operate at less than 4000 cycles per minute to maintain the gas pressure.

  The maximum dimension of the mass spectrometer can be less than 35 cm. The total mass of the mass spectrometer can be less than 4.5 kg.

  Embodiments of the mass spectrometer can include any other features disclosed herein, as appropriate, in any combination.

  In another aspect, the present disclosure uses a single mechanical pump that operates at less than 6000 cycles per minute to reduce the gas pressure in at least two of the mass spectrometer ion source, ion trap, and ion detector. And a method comprising: detecting ions generated by the ion source according to a mass-to-charge ratio of the ions, wherein the at least two of the ion source, the ion trap, and the ion detector are provided. In one, the gas pressure is maintained between 100 mTorr and 100 Torr.

  Embodiments of the method can include one or more of the following features.

  The gas pressure in the ion source and the ion trap can be maintained between 100 mTorr and 100 Torr. The gas pressure in the ion trap and the detector can be maintained between 100 mTorr and 100 Torr. The method may include maintaining a gas pressure that is less than 10 Torr in at least two of the ion source, the ion trap, and the ion detector. The method may further include maintaining the same gas pressure in the ion source, the ion trap, and the ion detector.

  The method may include introducing a mixture of gas particles into a gas path connecting the ion source, the ion trap, and the ion detector, and the gas particle mixture is analyzed. Gas particles and atmospheric gas particles are included, and the mixture of gas particles is not filtered to remove atmospheric gas particles before being introduced into the gas path.

  The method can include operating the mechanical pump at a rate of less than 4000 cycles per minute to control the gas pressure.

  Embodiments of the method can include any other features disclosed herein, in any combination, as appropriate.

  Unless defined otherwise, scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present subject matter, suitable methods and materials are described below. All publications, patent applications, patents, and other cited references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative and not intended to be limiting.

  The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the detailed description, drawings, and claims.

FIG. 1A is a schematic diagram of a compact mass spectrometer. FIG. 1B is a cross-sectional view of one embodiment of a mass spectrometer. FIG. 1C is a cross-sectional view of another embodiment of a mass spectrometer. FIG. 1D is a schematic diagram of a mass spectrometer with components attached to a support base. FIG. 1E is a schematic diagram of a mass spectrometer with a pluggable module. FIG. 1F is a schematic view of an attachment mechanism for connecting a mass spectrometer module to a support base. FIG. 2A is a schematic diagram of a glow discharge ion source. FIG. 2B is a schematic diagram of a glow discharge ion source. FIG. 2C is a schematic diagram showing an electrode of an ion source provided with an aperture. FIG. 2D is a schematic diagram showing an electrode of an ion source having an aperture. FIG. 2E is a schematic diagram showing an electrode of an ion source provided with an aperture. FIG. 2F is a schematic diagram showing an electrode of an ion source having an aperture. FIG. 2G is a schematic diagram showing an electrode of an ion source provided with an aperture. FIG. 2H is a schematic diagram showing an electrode of an ion source having an aperture. FIG. 2I is a graph showing the bias charge applied to the electrode of the ion source. FIG. 2J is a graph showing the bias charge applied to the electrode of the ion source to clean the ion source. FIG. 2K is a schematic diagram of a capacitor discharge ion source. FIG. 3A is a cross-sectional view of one embodiment of an ion trap. FIG. 3B is a schematic diagram of another embodiment of an ion trap. FIG. 3C is a cross-sectional view of the ion trap of FIG. 3B. FIG. 4A is a schematic diagram of a voltage source. FIG. 4B is a graph showing an unamplified modulation signal of the ion trap. FIG. 4C is a graph showing the modified signal of the ion trap. FIG. 4D is a graph showing a reference carrier waveform. FIG. 4E is a graph showing the amplified modulation signal of the ion trap. FIG. 4F is a diagram showing a resonance circuit for amplifying the signal of FIG. 4E. FIG. 5A is a perspective view of one embodiment of a Faraday cup charged particle detector. FIG. 5B is a schematic diagram of the Faraday cup detector of FIG. 5A. FIG. 5C is a schematic diagram of another embodiment of a Faraday cup detector. FIG. 5D is a schematic diagram of a Faraday cup detector array. FIG. 6A is a schematic diagram of a pressure regulation subsystem with a scroll pump. FIG. 6B is a schematic view of a scroll pump flange. FIG. 7A is a perspective view of a compact mass spectrometer. FIG. 7B is a cross-sectional view of an embodiment of a compact mass spectrometer. FIG. 7C is a cross-sectional view of an embodiment of a compact mass spectrometer. FIG. 8A is a flowchart showing a series of steps for measuring mass spectral information and displaying information about a sample. FIG. 8B is a schematic diagram of one embodiment of a compact mass spectrometer. FIG. 8C is a flowchart showing a series of steps for measuring mass spectral information and adjusting the configuration of the mass spectrometer.

  Like reference symbols in the various drawings indicate like elements.

I. Overview Mass spectrometers used for chemical identification are typically large, complex instruments that consume significant power. These instruments are heavy and too bulky to carry, so they are limited to use in environments that can be substantially fixed. In addition, traditional mass spectrometers are typically expensive and highly trained to interpret the spectrum of ion information patterns produced by these instruments and infer the identity of the chemicals being analyzed. Requires an operator.

  To achieve high sensitivity and resolution, conventional mass spectrometers typically use a wide variety of components designed for operation at low gas pressures. For example, conventional ion detectors, such as electronic amplifier tubes, do not work effectively at pressures generally above 10 millitorr. As another example, thermionic emitters used in conventional ion sources are only suitable for operation at pressures of less than about 10 millitorr at best and are generally not usable even if the oxygen concentration is not so high. In addition, conventional mass spectrometers typically have a mass analyzer with a geometry specifically designed for operation only at pressures below 10 mTorr, specifically at pressures in the microtorr range. As a result, a conventional mass spectrometer is not only configured for low pressure operation, but a conventional mass spectrometer cannot operate at higher gas pressures because of the components it uses. Higher gas pressures can, for example, destroy some components of conventional mass spectrometers. Although not as dramatic, some components are simply inoperable at higher gas pressures or are very poorly operated, allowing these mass spectrometers to obtain useful mass spectral information. Disappear. Consequently, operation at higher pressures (eg, pressures above 100 millitorr) requires mass spectrometers with very different configurations and components.

  To achieve low pressure, conventional mass spectrometers typically include a series of pumps that evacuate the internal volume of the analyzer. For example, a conventional mass spectrometer can include a roughing pump that rapidly reduces the internal pressure of the system and a turbomolecular pump that further reduces the internal pressure to a microtorr value. Turbomolecular pumps are large and consume considerable power. However, these considerations are only of secondary importance in conventional mass spectrometers, and the most important consideration is achieving high resolution in the measured mass spectrum. By using the above-described components operating at low pressure, conventional mass spectrometers can typically achieve a resolution of 0.1 atomic mass units (amu) or better.

  In contrast to conventional mass spectrometers that are heavy and bulky, the compact mass spectrometer disclosed herein is designed for low power and high efficiency operation. In order to achieve low power operation, the compact mass spectrometer disclosed herein does not include turbomolecular pumps or other high power consumption vacuum pumps. Instead, this compact mass spectrometer typically includes only a single mechanical pump that operates at a low frequency, which significantly reduces power consumption.

  By using a smaller pump, the compact mass spectrometer disclosed herein typically operates in the pressure range of 100 millitorr to 100 torr, which is higher than the operating pressure range of conventional mass spectrometers. It is quite high. Conventional mass spectrometers cannot be modified to operate at these higher pressures because the components used in conventional mass spectrometers (e.g., electron multipliers, thermionic emitters) And the ion trap) do not function in the pressure range in which the compact mass spectrometer disclosed herein operates. Furthermore, conventional mass spectrometers are generally not modified to operate at higher internal pressures because doing so reduces the resolution of the mass spectrum measured using the device. When using such a device, there is no reason to modify the device to lower the resolution because it is a general goal to obtain a mass spectrum with the highest possible resolution.

  However, the compact mass spectrometer disclosed herein provides the user with different types of information than a conventional mass spectrometer. In particular, the compact mass spectrometer disclosed herein typically reports information such as the name of the chemical being analyzed, hazard information associated with the substance, and / or the type to which the substance belongs. To do. The compact mass spectrometer disclosed herein can, for example, also report whether the material is a specific target material. Typically, the recorded mass spectrum is not displayed to the user unless the user activates a control means that causes the spectrum to be displayed. As a result, unlike conventional mass spectrometers, the compact mass spectrometer disclosed herein does not need to acquire mass spectra with maximum resolution. Instead, further increase in resolution is not a significant performance requirement if the resulting spectrum is of high quality to determine the information reported to the user.

  By operating at lower resolutions (typically, mass spectra are obtained with resolutions between 1 amu and 10 amu), the compact mass spectrometer disclosed herein can achieve conventional mass spectrometry. Compared with the analyzer, power consumption is considerably reduced. For example, the compact mass spectrometer disclosed herein comprises a small ion trap that operates efficiently at a pressure of 100 millitorr to 100 torr to separate ions with different mass to charge ratios, Because of its small size, it consumes significantly less power than conventional mass analyzers such as ion traps. For example, as the size of a cylindrical ion trap decreases, the maximum voltage applied to this trap for separating ions decreases and the frequency at which the voltage is applied increases. As a result, the size of the inductor and / or resonator used in the power supply circuit is reduced, and the size and power consumption requirements of other components used to generate the maximum voltage are also reduced.

  In addition, the compact mass spectrometer disclosed herein is a glow discharge ionization source and / or that further reduces power consumption compared to an ion source such as a thermionic emitter typically provided in conventional mass spectrometers. An efficient ion source such as a capacitor discharge ionization source is provided. The compact mass spectrometer disclosed herein uses an efficient and low power detector, such as a Faraday detector, rather than an electron multiplier with higher power consumption provided by conventional mass spectrometers. ing. Because of these low power components, the compact mass spectrometer disclosed herein operates efficiently and has relatively low power consumption. They are powered from a standard battery-based power source (eg, a lithium-ion battery) and are portable with a hand-held form factor.

  Conventional mass spectrometers provide a high resolution mass spectrum directly to the user, and are therefore generally unsuitable for applications involving portable scanning of materials by untrained personnel. Especially for applications such as on-site security scans at transportation hubs such as airports and train stations, conventional mass spectrometers are not practical as a solution. In contrast, such applications benefit from mass spectrometers that are compact, require relatively little power to operate, and provide information that can be easily interpreted by highly untrained personnel, as described above. . A compact, low cost mass spectrometer is also useful for a variety of other applications. For example, such devices can be used in the laboratory to quickly describe the properties of unknown compounds. Since these are low cost and have a small footprint, laboratories can be provided with personal analyzers, reducing or eliminating the need to reserve analysis time in a centralized mass spectrometer facility. The compact mass spectrometer can also be used as a medical diagnostic test in both the clinical environment and individual patient residences. Engineers performing these tests can easily interpret the information provided by such analyzers to provide real-time evaluative information to patients, or provide rapidly updated information to healthcare facilities, physicians, and other healthcare professionals. Can be given to a person.

  The present disclosure is a small, low-power mass spectrometer that includes a variety of information and / or class to which the substance belongs (e.g., acid, base, strong oxidizing substance) A mass spectrometer that provides a user with information about explosives, nitrated compounds, hazard information associated with the substance, and relevant contextual information including safety instructions and / or information. These analyzers operate at higher internal gas pressures than conventional mass spectrometers. By operating at higher pressures, the size and power consumption of these compact mass spectrometers are significantly reduced compared to conventional mass spectrometers. Furthermore, although these analyzers operate at higher pressures, their resolution is sufficient to accurately identify and quantify a wide variety of chemicals.

  FIG. 1A is a schematic diagram of one embodiment of a compact mass spectrometer 100. The analyzer 100 includes an ion source 102, an ion trap 104, a voltage source 106, a controller 108, a detector 118, a pressure adjustment subsystem 120, and a sample inlet 124. The sample inlet 129 includes a valve 129. The analyzer 100 optionally includes a buffer gas source 150. The components of the analyzer 100 are accommodated in the housing 122. The controller 108 includes an electronic processor 110, a user interface 112, a storage device 114, a display device 116, and a communication interface 117.

  Controller 108 provides control lines 127a-127g to ion source 102, ion trap 104, detector 118, pressure regulation subsystem 120, voltage source 106, valve 129, and optional buffer gas source 150, respectively. Connected through. Control lines 127a-127g allow controller 108 (eg, electronic processor 110 within controller 108) to issue operational commands to each component to which it is connected. Such commands may include, for example, signals that activate the ion source 102, ion trap 104, detector 118, pressure regulation subsystem 120, valve 129, and buffer gas source 150. Commands for operating the various components of analyzer 100 may include instructions that cause voltage source 106 to apply a potential to these components. For example, to activate the ion source 102, the controller 108 can send a command to the voltage source 106 to apply a potential to the electrodes of the ion source 102. As another example, to activate the ion source 104, the controller 108 can send a command to the voltage source 106 to apply a potential to the electrodes of the ion trap 104. As yet another example, to activate the detector 118, the controller 108 can send a command to the voltage source 106 to apply a potential to the sensing element of the detector 118. The controller 108 also provides signals to operate the pressure regulation subsystem 120 (eg, via the voltage source 106) to control gas pressure within the various components of the analyzer 100, and gas particles to the sample inlet. A signal can be transmitted to valve 129 (eg, via voltage source 106) for introduction into analyzer 100 via 124.

  In addition, the controller 108 can receive signals from each component of the analyzer 100 via control lines 127a-127g. For example, such signals may include information regarding operating characteristics of the ion source 102 and / or the ion trap 104 and / or the detector 118 and / or the pressure regulation subsystem 120. The controller 108 can also receive information regarding the ions detected by the detector 118. This information can include the ionic current measured by the detector 118, which is related to the abundance of ions with a particular mass to charge ratio. Because the specific ion abundance is measured by the detector 118, this information can also include information regarding the voltage applied to the electrode of the ion trap 104. These applied voltages are related to the mass to charge ratio values of these ions. By correlating this voltage information with the measured abundance information, the controller 108 can determine the abundance of ions as a function of the mass-to-charge ratio and use this information in the form of a mass spectrum using the display 116. Can present.

  The voltage source 106 is connected to the ion source 102, the ion trap 104, the detector 118, the pressure adjustment subsystem 120, and the controller 108 via control lines 126a-127e, respectively. The voltage source 106 supplies potential and power to each of these components via control lines 126a-e. The voltage source 106 sets a reference potential corresponding to electrical ground with a relative voltage of 0 volts. The potential applied by the voltage source 106 to the various components of the analyzer 100 is referenced to this ground potential. In general, the voltage source 106 is configured to apply a positive potential and a negative potential to the components of the analyzer 100 with respect to the reference ground potential. By applying potentials with different signs to these components (eg, to the electrodes of these components), electric fields with different signs are generated within these components, causing ions to move in various directions. Thus, by applying an appropriate potential to the components of the analyzer 100, the controller 108 can control the movement of ions within the analyzer 100 (via the voltage source 106).

  The ion source 102, the ion trap 104, and the detector 118 are connected such that a gas path 128, which is an internal passage for gas particles and ions, extends between these components. A sample inlet 124 and a pressure regulation subsystem 120 are also connected to the gas path 128. If an optional buffer gas source 150 is provided, it is also connected to the gas path 128. Some portions of the gas path 128 are shown schematically in FIG. 1A. In general, gas particles and ions can move in any direction within the gas path 128, and the direction of movement can be controlled by the configuration of the analyzer 100. For example, by applying an appropriate potential to the electrodes of the ion source 102 and the ion trap 104, ions generated in the ion source 102 can be directed to flow into the ion trap 104 from the ion source 102.

  FIG. 1B is a partial cross-sectional view of the mass spectrometer 100. As shown in FIG. 1B, the output aperture 130 of the ion source 102 is coupled to the input aperture 132 of the ion trap 104. In addition, the output aperture 134 of the ion trap 104 is coupled to the input aperture 136 of the detector 118. As a result, ions and gas particles can flow in any direction between the ion source 102, the ion trap 104, and the detector 118. During operation of the analyzer 100, the pressure regulation subsystem 120 operates to reduce the gas pressure in the gas path 128 to a value below atmospheric pressure. As a result, the gas particles to be analyzed enter the sample inlet 124 from the environment around the analyzer 100 (eg, the environment outside the housing) and enter the gas path 128. Gas particles that enter the ion source 102 via the gas path 128 are ionized by the ion source 102. These ions propagate from the ion source 102 to the ion trap 104 where they are trapped by the electric field formed when the voltage source 106 applies an appropriate potential to the electrode of the ion trap 104.

  The trapped ions circulate in the ion trap 104. In order to analyze the circulating ions, the voltage source 106 changes the amplitude of the radio frequency trapping field applied to one or more electrodes of the ion trap 104 under the control of the controller 108. Changes in amplitude occur repeatedly and define the sweep frequency of the ion trap 104. As the electric field amplitude changes, ions with a particular mass to charge ratio fall off the trajectory and some are ejected from the ion trap 104. The ejected ions are detected by the detector 118, and information about these detected ions (eg, the measured ion current from the detector and the voltage applied to the ion trap 104 when a specific ion current is measured). It is transmitted to the controller 108.

  Although the sample inlet 124 is located in FIGS. 1A and 1B so that gas particles enter the ion trap 104 from the environment outside the housing 122, more generally, the sample inlet 124 is also located elsewhere. it can. For example, FIG. 1C shows a partial cross-sectional view of the analyzer 100 in which the sample inlet 124 is positioned such that gas particles enter the ion source 102 from an environment outside the housing 122. In addition to the configuration shown in FIG. 1C, the sample inlet 124 can be disposed at any position along the gas path 128 as long as gas particles can enter the gas path 128 from the environment outside the housing 122 depending on the position.

  Communication interface 177 may generally be a wired or wireless (or both) communication interface. The controller 108 can be configured to communicate via a communication interface 177 with a wide variety of devices, including remote computers, cell phones, and surveillance and security scanners. Communication interface 177 may be configured to send and receive data via various networks including, but not limited to, Ethernet networks, wireless WiFi networks, cellular networks, and Bluetooth wireless networks. The controller 108 communicates with the remote device using the communication interface 177 to record various information including the operation and configuration settings of the analyzer 100, the recording of the mass spectrum of known substances, the hazards associated with the particular substance, It is possible to obtain information regarding the target substance, including the type of the compound to which the target substance belongs and / or the spectral characteristics of the known substance. This information can be used by the controller 108 to analyze the sample measurements. In addition, the controller 108 can send information to the remote device that includes a warning message when a particular substance (eg, dangerous substance and / or explosive) is detected by the analyzer 100.

The mass spectrometer disclosed herein is compact and capable of low power operation. To achieve compact size and low power operation, various analyzer components, including ion source 102, ion trap 104, detector 118, pressure regulation subsystem 120, and voltage source 106 are: Carefully designed and configured to minimize space requirements and power consumption. In conventional mass spectrometers, the vacuum pump used to achieve a low internal operating pressure (eg, 1 × 10 ⁻³ Torr or much lower) is large and consumes a significant amount of power. For example, to achieve such a pressure, a conventional mass spectrometer typically has one roughing pump that rapidly reduces the internal system pressure from atmospheric to about 0.1-10 torr, and an internal system pressure of 10 torr. Two or more series of pumps are used, including one or more turbomolecular pumps that reduce from 1 to the desired internal operating pressure. Both roughing pumps and turbomolecular pumps are mechanical pumps that require a significant amount of power to operate. Rough pumps (which can include, for example, piston pumps) typically generate significant mechanical vibrations. Turbomolecular pumps are typically sensitive to both vibrations and mechanical shocks, and produce high-gyroscopic effects due to their high rotational speed. As a result, conventional mass spectrometers have sufficient power to meet the power consumption requirements of these vacuum pumps and an isolation mechanism (eg, vibration isolation and / or rotation) to ensure continuous operation of these pumps. Isolation mechanism). Conventional mass spectrometers may require that an internal turbomolecular pump be moved during operation as it may be destroyed as it may be destroyed. As a result, due to the combination of vacuum pump and power source used in conventional mass spectrometers, they are large, heavy and cannot be moved.

  In contrast, the mass spectrometers and methods disclosed herein are compact and mobile, and achieve low power operation. These properties are achieved in part by omitting turbomolecules, roughing, and other large mechanical pumps that are commonly found in conventional analyzers. Instead of these large pumps, a small, low power single mechanical pump is used to control the gas pressure in the mass spectrometer system. A single mechanical pump used in the mass spectrometer system disclosed herein cannot reach as low a pressure as a conventional turbomolecular pump. As a result, the system disclosed herein operates at a higher internal gas pressure than conventional mass spectrometers.

  As described in more detail below, operation at higher pressures generally reduces the resolution of the mass spectrometer due to collision-induced line broadening and charge exchange between molecular fragments. The term “degree of resolution” is defined as the half-wave height full width value (FWHM) of the measured mass peak. The resolution of a particular mass spectrometer measures the FWHM for all peaks that appear within the mass-to-charge ratio range of 100-125 amu and corresponds to a single peak (e.g., a close set of two or more peaks) The maximum FWHM corresponding to the resolution is selected as the resolution. In order to obtain the degree of decomposition, a chemical substance having a known mass spectrum such as toluene can be used.

  Although the resolution of a mass spectrometer may decrease when operating at higher pressures, the mass spectrometer disclosed herein does not affect the usefulness of the analyzer even if the resolution decreases. It is configured as follows. In particular, the mass spectrometer disclosed herein is not a mass-resolved spectrum of molecular ions, as is usually done with conventional mass spectrometers, as the chemical of interest is scanned using the analyzer. The meter is configured to report information related to the identity of the substance to the user. In some embodiments, the algorithm used in the mass spectrometer disclosed herein compares the measured ion fragmentation pattern to a known fragmentation pattern to determine the identity of the substance of interest and / or the object It is possible to specify information such as one or more types of compounds to which the target substance belongs. In some embodiments, these algorithms can include specialized systems that identify information regarding the identity of the material of interest. For example, a digital filter can be used to find the characteristics of a measured spectrum of a substance of interest that matches or matches a specific target substance based on the presence or absence of those characteristics in the spectrum. Can be identified as not.

  When the controller 108 performs the above analysis, the low resolution due to high pressure operation can be compensated by the system disclosed herein. That is, if a reliable correspondence between the measured fragmentation pattern and the reference information can be achieved, the degradation in resolution due to high pressure operation is almost insignificant for the mass spectrometer users disclosed herein. It is. Thus, although the mass spectrometer disclosed herein operates at a higher pressure than conventional mass spectrometers, the user is more likely to identify the substance than to examine the ion fragmentation pattern of the substance in question. Maintains utility in a wide range of security scans, medical diagnostics, laboratory analysis, etc. where there is a major interest and the user is not highly trained in the interpretation of mass spectra.

  By using a single miniature mechanical pump, the mass spectrometer disclosed herein is significantly smaller in weight, size, and power consumption than a conventional mass spectrometer. Therefore, the mass spectrometer disclosed in the present specification is equipped with a small mechanical pump and has an internal gas pressure (a gas path 128, an ion source 102 connected to the gas path 128, an ion trap 104, a detector 118). Gas pressure) between 100 mTorr and 100 Torr (e.g. between 100 mTorr and 500 mTorr, between 500 mTorr and 100 Torr, between 500 mTorr and 10 Torr, between 500 mTorr and 50 Torr, A pressure regulation subsystem 120 that maintains between millitorr and 1 torr. In some embodiments, the pressure regulation subsystem may have an internal gas pressure greater than 100 millitorr of the mass spectrometer disclosed herein (e.g., greater than 500 millitorr, greater than 1 torr, greater than 10 torr, 20 It is configured to maintain (exceeding Thor).

  At the pressures described above, the mass spectrometer disclosed herein detects ions with a resolution of 10 amu or better. For example, in some embodiments, the resolution of a mass spectrometer disclosed herein is 10 amu or better (e.g., 8 amu or better, as measured above). 6 amu or better, 5 amu or better, 4 amu or better, 3 amu or better, 2 amu or better, 1 amu or better Better). In general, any of these resolutions can be achieved at any of the pressures described above using the mass spectrometers disclosed herein.

  In addition to the pump, the pressure regulation subsystem 120 can include a variety of other components. In some embodiments, the pressure regulation subsystem 120 includes one or more sensors. The one or more sensors can be configured to measure a gas pressure in a fluid line, such as the gas path 128, to which the pressure regulation subsystem 120 is connected. The measured gas pressure can be transmitted to the pump and / or controller 108 in the pressure regulation subsystem 120 and further displayed on the display device 116. In some embodiments, the pressure regulation subsystem 120 can include one or more valves, apertures, sealing members, and / or other elements for fluid treatment such as fluid lines.

  In order to ensure that this pressure regulation subsystem functions efficiently to control the internal pressure of the mass spectrometer disclosed herein, the internal volume of these analyzers (eg, pumped by the pressure regulation subsystem) Volume) is significantly reduced compared to the internal volume of a conventional mass spectrometer. The reduced internal volume has the added benefit of reducing the overall size of the mass spectrometer disclosed herein, which makes the analyzer compact and portable and allows one-handed operation by the user. become.

As shown in FIGS. 1B and 1C, the internal volume of the mass spectrometer disclosed herein includes the internal volume of the ion source 102, ion trap 104, and detector 118 and the area between these components. More generally, the internal volume of the mass spectrometer disclosed herein corresponds to the volume of the gas path 128, ie, the volume of all connected spaces in the mass spectrometer 100 through which gas particles and ions can circulate. In some embodiments, the internal volume of the mass spectrometer 100 is 10 cm ³ or less (e.g., 7.0 cm ³ or less, 5.0 cm ³ or less, 4.0 cm ³ or less, 3.0 cm ³ or less, 2.5 cm ³ or less, 2.0 cm Hereinafter, 1.5 cm ³ or less and 1.0 cm ³ or less.

  In some embodiments, the mass spectrometers disclosed herein are fully integrated on a single support base. FIG. 1D is a schematic diagram of one embodiment of a mass spectrometer 100 with all of its components integrated on a single support base 140. As shown in FIG. 1D, the ion source 102, the ion trap 104, the detector 118, the controller 108, and the voltage source 106 are attached to and electrically connected to the support base 140, respectively. The support base 140 is a printed circuit board and includes control lines that extend between the components of the analyzer 100. Thus, for example, the voltage source 106 includes control lines (eg, control lines) that are incorporated into the support base 140 to the ion source 102, ion trap 104, detector 118, controller 108, and pressure regulation subsystem 120. 126a-127e) to supply power. Further, the ion source 102, the ion trap 104, the detector 118, the pressure adjustment subsystem 120, and the voltage source 106 have control lines (for example, control lines 127a-127e) incorporated in the support base 140, respectively. The controller 108 can transmit and receive electrical signals to and from each of these components via the support base 140.

  Integration on a single support base, such as a printed circuit board, provides many important advantages. The support base 140 provides a stable platform for the components of the analyzer 100 to ensure that each component is installed stably and safely, and the components break when the analyzer 100 is handled poorly Reduce the possibility of doing. In addition, mounting all components on a single support base simplifies the manufacturing of the analyzer 100, since the support base 140 becomes a reproducible template for positioning these various components and their connection to each other. Is done. In addition, by integrating all control lines into this support base, both power and control signals are transmitted between the components through the support base 140, thereby maintaining the integrity of the electrical connection between the components. . That is, such connections are less susceptible to wear and / or breakage than connections formed by individual wires extending between components.

  In addition, by integrating the components of the analyzer 100 onto a single support base, the analyzer 100 has a compact form factor. In particular, the maximum dimension of the support base 140 (e.g., the maximum linear distance between any two points on the support base 140) is 25 cm or less (e.g., 20 cm or less, 15 cm or less, 10 cm or less, 8 cm or less, 7 cm or less, 6 cm or less).

  As shown in FIG. 1D, the support base 140 is attached to the housing 122 using attachment pins 145. In some embodiments, the mounting pins 145 isolate the support base 140 (and components attached to the support base 140) from mechanical shock. For example, the mounting pin 145 can include a shock absorbing material (eg, a stretchable material such as soft rubber) to cushion the support base 140 from mechanical shock. As another example, a grommet or spacer formed from an impact cushioning material can be disposed between the support base 140 and the housing 122 to cushion the support base 140 against mechanical impact.

  In some embodiments, the mass spectrometer disclosed herein includes a pluggable and replaceable module in which a plurality of system components are integrated. FIG. 1E is a schematic diagram of one embodiment of a mass spectrometer 100 that includes a pluggable and replaceable module 148 and a support base 140 configured to receive the module 148. The ion source 102, the ion trap 104, the detector 118, and the sample inlet 124 are each integrated in a module 148.

  Module 148 also includes a plurality of electrodes 142 extending outwardly from the module. Within module 148, electrode 142 is connected to each of the components of this module such as, for example, ion source 102, ion trap 104, and detector 118.

  FIG. 1E also shows a support base 140 (eg, a printed circuit board) to which the controller 108, voltage source 106, and pressure regulation subsystem 120 are attached. Support base 140 includes a plurality of electrodes 144 configured to removably engage and disengage electrodes 142 of module 148. In some embodiments, for example, electrode 142 is a pin and electrode 144 is a socket configured to accommodate electrode 142. Alternatively, electrode 144 may be a pin and electrode 142 may be a socket configured to receive these pins. The module 148 can be connected to the support base 140 by applying a force in the direction indicated by the arrow in FIG. 1E while the electrode 142 of the module 148 is aligned with the corresponding electrode 144 of the support base. The support base 140 can be detachably connected or disconnected. The module 148 can be separated from the support base 140 by applying a force in the direction opposite to the arrow.

  The electrode 144 of the support base 140 is connected to the controller 108 and the voltage source 106 as shown in FIG. 1E. Once the electrodes 142 and 144 are connected, the controller 108 can send and receive signals to and from the components integrated within the module 148 as described above with respect to the control line 127. In addition, the voltage source 106 can supply power to each component integrated within the module 148 as described above with respect to the control line 126.

  A pressure regulation subsystem 120 attached to the support base 140 is connected to the manifold 121 via a conduit 123. When the module 148 is connected to the support base 140, the manifold 121 including one or more apertures 125 is positioned on the support base 140 such that a sealed fluid connection is established between the manifold 121 and the module 148. The In particular, a fluid connection is established between the aperture 125 of the manifold 121 and the corresponding aperture of the module 148 (not shown in FIG. 1E). The apertures of module 148 can be formed in the walls of ion source 102, ion trap 104, and / or detector 118. Once this sealed fluid connection is established, the pressure regulation subsystem 120 can control the gas pressure in the components of this module by pumping gas particles from the 148 module through the manifold 121.

  Other configurations of module 148 are possible. In some embodiments, the detector 118 is not part of the module 148 but is instead attached to the support base 140. In such a configuration, when the module 118 is connected to the support base 140, the detector 118 is positioned on the support base 140 such that a sealed fluid connection is provided between the ion trap 104 and the detector 118. Once the sealed fluid connection is established, circulating ions in the ion trap 104 can be ejected from the trap and detected using the detector 118, and the pressure regulation subsystem 120 can be detected in the detector 118. A low gas pressure (eg, between 100 mTorr and 100 Torr) can be maintained.

  In some embodiments, the pressure regulation subsystem 120 can be integrated into the module 148. For example, the pressure regulation subsystem 120 can be attached to the lower surface of the ion trap 104 and connected directly to the gas path 128 in the module 148. The pressure regulation subsystem 120 can also be electrically connected to the electrodes of the module 148. When the module 148 is connected to the support base 140, the pressure regulation subsystem 120 can send and receive electrical signals through the electrode 142 between the controller 108 and the voltage source 106.

  The modular configuration of the mass spectrometer 100 shown in FIG. 1E provides several advantages. For example, during operation of the mass spectrometer 100, some components may be contaminated by analyte residues. For example, analyte residues may adhere to the walls of the ion trap 104, reducing the efficiency with which the ion trap 104 separates ions, and may adversely affect the analysis of other substances. By integrating the ion trap 104 into the module 148, if the ion trap 104 becomes contaminated, the entire module 148 can be easily and quickly replaced, and the mass spectrometer 100 can be put into operation by an untrained user in the field. It is guaranteed that you can get back quickly. Similarly, if either the ion trap 104 or the detector 118 is contaminated or fails, the module 148 can be easily replaced by the user of the analyzer 100 to return the analyzer 100 to operation.

  The module configuration shown in FIG. 1E ensures that the analyzer 100 is compact and portable. In some embodiments, for example, the maximum dimension of the support base 148 (maximum linear distance between any two points on the module 148) is 10 cm or less (e.g., 9 cm or less, 8 cm or less, 7 cm or less, 6 cm Hereinafter, 5 cm or less, 4 cm or less, 3 cm or less, 2 cm or less, 1 cm or less.

  Modules 148 with degraded functionality (eg, modules contaminated with analyte particles attached to the inner wall of ion source 102, ion trap 104, and / or detector 118) can be regenerated and reused. In some embodiments, the module 148 can be heated when installed in the analyzer 100 to return the module 148 to normal operation. Heating can be performed by a heating element 127 attached to the support base 140. As shown in FIG. 1E, when the module 148 is connected to the support base 140, the heating element 127 is replaced with one or more components of the module 148 (eg, the ion source 102, the ion trap 104, and the detector 118). The heating element 127 is positioned on the support base 140 so as to contact

  The controller 108 can be configured to operate the heating element 127 by instructing the voltage source 106 to apply an appropriate potential to the heating element 127. The start of heating and the temperature and duration of heating can be controlled by the user of the analyzer 100 by, for example, operating the control means of the display device 116 and / or inputting user configuration settings into the storage device 114. In some embodiments, the controller 108 can be configured to automatically determine when it is appropriate to play the module 148. For example, the controller 108 can monitor the detected ion current over a period of time and within a specific time period (e.g., 1 hour or more, 5 hours or more, 10 hours or more, 24 hours or more, 2 days or more, 5 days or more, 10 days As described above, when the ionic current decreases by exceeding the threshold amount (for example, 25% or more, 50% or more, 60% or more, 70% or more), the controller 108 determines that the module 148 needs to be regenerated.

  The heating element 127 is attached to the support base 140 in FIG. 1E, but other configurations are possible. In some embodiments, for example, the heating element 127 is part of the module 148 and is in direct contact with some or all of the components of the module 148 (eg, the ion source 102, the ion trap 104, and the detector 118). Can be attached.

  In some embodiments, the module 148 can be removed from the analyzer 100 for regeneration. For example, if the function of module 148 appears to be degraded (eg, by determination by the user of analyzer 100 or by automatic determination by controller 108 using the criteria described above), module 148 may be And can be heated to restore normal operation. Heating can be performed in a variety of ways, including heating in a general purpose furnace. In some embodiments, the analyzer 100 can include a dedicated plug-in heater that includes a slot configured to accommodate the module 148. When a module is inserted into this slot and the heater is activated, the module is heated and its function is restored.

  Although the ion source 102, ion trap 104, and detector 118 are generally configured to detect and identify a wide variety of chemicals, in some embodiments these components are of a particular type. It has been specialized to detect substances. In some embodiments, the ion source 102 can be specifically configured for use with certain materials. For example, different potentials can be applied to the electrodes of the ion source 102 to generate positive ions or negative ions from the gas particles. Further, the efficiency of ionizing a specific substance can be controlled by changing the magnitude of the potential applied to the electrode of the ion source 102. In general, different materials have different ionization affinities depending on their chemical structure. By adjusting the polarity and potential difference between the electrodes of the ion source 102, ionization of various substances can be carefully controlled.

  In some embodiments, the ion trap 104 can be specifically configured for use with certain materials. For example, the internal dimensions (eg, inner diameter) of the ion trap 104 can be selected to favor the capture and detection of ions with higher mass to charge ratios.

  In some embodiments, the internal gas pressure within one or more of the ion source 102, ion trap 104, and detector 118 favors a softer or harder ionization mechanism or positive or negative ion production. You can choose to be. Furthermore, the magnitude and polarity of the potential applied to the electrodes of the ion source 102 and ion trap 104 can be selected to favor a particular ionization mechanism. As mentioned above, different materials may have different ionization affinity, and one method may ionize more efficiently (eg, by one mechanism) than another. By adjusting the gas pressure in the analyzer 100 and the potential applied to the various electrodes, the analyzer can be adapted, and in particular, various substances and types of substances can be detected. Further, by adjusting the geometry of the ion trap 104 and / or the potential applied to its electrodes, the mass window of the ion trap 104 (eg, the ion mass-to-charge ratio that can be maintained in the circulation trajectory within the ion trap 104). Range).

  In some embodiments, the ion source 102 can include a specific type of ionizer specialized for a specific type of material. For example, ion sources based on glow discharge ionization, electrospray mass ionization, capacitor discharge ionization, dielectric barrier discharge ionization, and any of the other types of ionizers disclosed herein can be used in the ion source 102.

  In some embodiments, the detector 118 can be specialized for a particular type of detection task. For example, the detector 118 can be any of the one or more detectors disclosed herein. These detectors have a specific configuration and / or any configuration within detector 118, such as an array type, with multiple detection elements, such as multiple Faraday cup detectors, as will be described later. Can be arranged. In addition to being specialized for the detection of specific substances, the detector 118 can be specialized for use with specific types of ion sources and ion traps. For example, the arrangement and type of detection elements in detector 118 can be selected to correspond to the arrangement of ion chambers in ion trap 104, particularly when ion trap 104 includes a plurality of ion chambers.

  In some embodiments, one or more inner surfaces of module 148 (eg, of ion source 102 and / or ion trap 104 and / or detector 118) are coated with one or more coatings and / or surface treatments. Can be included. These coatings and / or surface treatments can be adapted for specific applications including detection of specific types of substances, operation within specific gas pressure ranges, and / or operation at specific applied potentials. Examples of coatings and / or surface treatments that can be used to customize module 148 for specific materials and / or applications include Teflon (more commonly, fluorinated polymer coatings), anodizing coatings , Nickel, and chrome.

  Other components of module 148 can also be adapted to detect specific substances or several types of substances. For example, in the sample inlet 124, a filter that allows only certain types of substances to pass through the analyzer 100 or similarly delays the passage of certain substances into the analyzer compared to the passage of other substances ( For example, the filter 706 in FIG. 7B described in a later item can be provided. In some embodiments, for example, the filter includes a HEPA filter (or similar type of filter) that removes solid, micron-sized particles such as dust particles from the flow of gas particles entering the sample inlet 124. Can be included. In some embodiments, the filter can include a filter based on a molecular sieve that removes water vapor from the flow of gas particles entering the sample inlet 124. Both of these types of filters do not filter atmospheric gas particles (eg, nitrogen and oxygen molecules) and allow the atmospheric gas particles to pass into gas path 128 of analyzer 100. With respect to a filter, such as filter 706, that does not remove or filter atmospheric gas particles in this disclosure, it should be understood that the filter passes at least 95% of the atmospheric gas particles that contact it.

  Thus, in some embodiments, the mass spectrometer 100 can include a number of interchangeable modules 148. Some of these modules can be identical and can serve as direct replacements for each other (eg, when contaminated). Other modules can be configured for various modes of operation. For example, multiple interchangeable modules 148 can be configured to detect different types of substances. A user operating the analyzer 100 can select a module that is appropriate for a particular type of material and plug the selected module into the support base 140 before starting the analysis. To analyze another type of material, the user simply separates the first module from the support base 140, selects a new module, and plugs the new module into the support base 140. As a result, reconfiguration of the components of the mass spectrometer 100 for a variety of different applications is quick and easy. The module can also be specifically configured for different types of measurements (eg, different ionization methods, different capture and / or discharge potentials applied to the electrodes of the ion trap 104, and / or different detection methods). In general, each of a number of interchangeable modules 148 can include any of the features disclosed herein. Thus, some of these modules can be different based on the ion source, some of these modules can be different based on the ion trap, and some of these modules can be different based on the detector. Some modules may differ from each other based on two or more of these components.

  In some embodiments, the module 148 can be secured to the support base 140 using one or more attachment mechanisms. Referring to FIG. 1F, the module 148 includes a first attachment mechanism 195 in the form of an elongated member that engages a second attachment mechanism 197 on the support base 140. In some embodiments, the extension member 195 can be positioned on the support base 140 and a complementary attachment mechanism is included in the module 148. In some embodiments, the attachment mechanism 195 can be a cam that rotationally engages the attachment mechanism 197, and the attachment mechanism 197 includes, for example, a recess configured to receive the cam. In some embodiments, one or more sealing members 193 (e.g., O-rings, gaskets, and / or other sealing members) made of a soft material such as rubber and / or silicon are disposed to support the module 148. The connection between the base 140 can be sealed.

  In some embodiments, the attachment mechanisms 195 and 197 can be keyed so that the module 148 is connected to the support base 140 in a single orientation only. Keying these attachment mechanisms has the advantage of preventing the user from attaching the module 148 in the wrong orientation.

  In some embodiments, other attachment mechanisms can be used. For example, the support base 140 and / or the module 148 can include a clamp 199 that secures the module 148 to the support base 140. One or more clamps can be used. Furthermore, a clamp may be used in addition to other attachment mechanisms.

  In the following sections, the various components of the mass spectrometer 100 are described in more detail, and the various modes of operation of the mass spectrometer 100 are also described.

II. Ion Source In general, the ion source 102 is configured to generate electrons and / or ions. If the ion source 102 generates ions directly from the gas particles being analyzed, then these ions are transferred from the ion source 102 to the ion trap 104 by an appropriate potential applied to the electrodes of the ion source 102 and ion trap 104. Moved. Depending on the magnitude and polarity of the potential applied to the electrode of the ion source 102 and the chemical structure of the gas particles being analyzed, the ions generated by the electrode of the ion source 102 can be positive ions or negative ions. In some embodiments, electrons and / or ions generated by the ion source 102 can collide with the neutral gas particles being analyzed and generate ions from these gas particles. During operation of the ion source 102, various ionization effects can occur simultaneously in the ion source 102 depending on the chemical structure of the gas particles being analyzed and the operating parameters of the ion source 102.

  By operating at a higher internal gas pressure than conventional mass spectrometers, the compact mass spectrometer disclosed herein can use a variety of ion sources. In particular, an ion source that is small and requires relatively little power to operate can be used with the analyzer 100. In some embodiments, for example, the ion source 102 may be a glow discharge ionization (GDI) source. In some embodiments, the ion source 102 may be a capacitor discharge ion source.

  Various other types of ion sources may be used with analyzer 100 depending on the amount of power and size required for operation. For example, other ion sources suitable for use with analyzer 100 include dielectric barrier discharge ion sources and thermionic emission sources. As another example, an ion source based on electrospray ionization (ESI) can be used in the analyzer 100. These ion sources include ion sources such as desorption electrospray ionization (DESI), secondary ion electrospray ionization (SESI), extraction electrospray ionization (EESI), and paper spray ionization (PSI). It is not limited to. As yet another example, an ion source based on laser desorption ionization (LDI) can be used in the analyzer 100. Such ion sources include, but are not limited to, ion sources such as electrospray assisted laser desorption ionization (ELDI) and matrix assisted laser desorption ionization (MALDI). In addition, the analyzer 100 uses ion sources based on techniques such as atmospheric solid state analysis probes (ASAP), desorption atmospheric pressure chemical ionization (DAPCI), desorption atmospheric pressure photoionization (DAPPI), and sonic spray ionization (SSI). be able to. An ion source based on an array of nanofibers (eg, an array of carbon nanofibers) is also suitable for use. Other aspects and features of the ion source described above, as well as other examples of ion sources suitable for use with the analyzer 100 are disclosed, for example, in the following publications, the entire contents of each of which are here: Cited and incorporated. Alberici et al., “Ambient mass spectrometry: bringing MS into the 'real world,'” analysis and biochemical analysis (Anal. Bioanal. Chem.) 398: 265-294 (2010); Harris et al., “Ambient Sampling / Ion Mass Spectrometry: Applications and Current Trends,” analysis Chem. 83: 4508-4538 (2011); and Chen et al., “Micro ionizers for portable mass spectrometers using double-gated vertical carbon nanofiber arrays (“ A Micro Ionizer for Portable Mass Spectrometers using Double-gated Isolated Vertically Aligned Carbon Nanofiber Arrays ''), IEEE Electronics Division Bulletin 58 (7): 2149-2158 (2011).

  The GDI source is particularly advantageous for use with the analyzer 100 because it is compact and suitable for low power operation. However, the glow discharge that occurs when these ion sources are used occurs only when the gas pressure is sufficient. Typically, for example, a GDI source is limited to a gas pressure of approximately 200 millitorr or greater during operation. At pressures below 200 millitorr, it may be difficult to maintain a stable glow discharge. As a result, GDI sources are not used in conventional mass spectrometers operating at pressures below 1 millitorr. However, since the mass spectrometer disclosed herein operates at gas pressures between 100 mTorr and 100 Torr, a GDI source can be used.

  FIG. 2A shows an example of a GDI source 200 that includes a front electrode 210 and a rear electrode 220. These two electrodes 210 and 220 together with the housing 122 form a GDI chamber 230. In some embodiments, the GDI source 200 can also include a housing surrounding the electrodes of the ion source. For example, in the embodiment shown in FIG. 2B, the GDI chamber 230 includes a separate housing 232 that surrounds the electrodes 210 and 220. The housing 232 is secured or attached to the housing 122 via a fastening element 250 (e.g., a clamp, screw, threaded part, or other type of fastener).

  As shown in FIGS. 2A and 2B, the front electrode 210 includes an aperture 202 through which gas particles to be analyzed enter the GDI chamber 230. As used herein, the term “gas particles” refers to gaseous atoms, molecules, or aggregated molecules that exist as separate entities in the gaseous state. For example, if the substance to be analyzed is an organic compound, the gas particles of the substance are individual molecules of the substance in the gas phase.

  The aperture 202 is surrounded by an insulating tube 204. In FIGS. 2A and 2B, the aperture 202 is connected to the sample inlet 124 (not shown), and the gas particles to be analyzed are separated from the GDI chamber by the atmospheric pressure difference between the atmosphere outside the analyzer 100 and the GDI chamber 230. Pulled into 230. In addition to the gas particles to be analyzed, atmospheric gas particles are also drawn into the GDI chamber 230 by this pressure difference. As used herein, the term “atmospheric gas particles” refers to atoms or molecules of gas in the air, such as molecules of oxygen gas or nitrogen gas.

  In some embodiments, additional gas particles can be introduced into the GDI source 200 to help generate electrons and / or ions in the ion source. For example, as described above with respect to FIG. 1A, the analyzer 100 can include a buffer gas source 150 connected to the gas path 128. Buffer gas particles from the buffer gas source 150 may be introduced directly into the GDI source 200 or may be introduced into another part of the gas path 128 and diffused into the GDI source 200. Such buffer gas particles can include nitrogen molecules and / or noble gas atoms (eg, He, Ne, Ar, Kr, Xe). Some of the buffer gas particles can be ionized by electrodes 210 and 220.

  Alternatively, in some embodiments, a mixture of gas molecules including gas particles to be analyzed and atmospheric gas particles is the only gas particle introduced into the GDI source 200. In such embodiments, only gas particles to be analyzed can be ionized in the GDI chamber 230. In some embodiments, both the analyzed gas particles and the introduced atmospheric gas particles can be ionized in the GDI chamber 230.

  In FIGS. 2A and 2B, the aperture 202 is located in the center of the front electrode 210, but more generally, the aperture 202 can be located at various locations in the GDI source 200. For example, the aperture 202 can be disposed on the side wall of the GDI chamber 230 and is connected to the sample inlet 124 here. Further, as described above, in some embodiments, the sample inlet 124 is configured so that the gas particles to be analyzed are drawn directly into another component of the analyzer 100, such as the ion trap 104 or detector 118. Can be positioned. As the gas particles are drawn into components other than the ion source 102, they diffuse into the ion source 102 via the gas path 128. Alternatively or additionally, if the gas particles to be analyzed are drawn directly into a component such as the ion trap 104, the ion source 102 can generate ions and / or electrons that are analyzed within the ion trap 104. The gas particles collide with each other and generate ions directly in the ion trap 104 from these gas particles.

  Thus, ions are generated from the gas particles at a variety of different locations depending on where in the analyzer 100 the gas particles to be analyzed are introduced (eg, the location of the sample inlet 124). Ions can be generated directly in the ion source 102 and the generated ions can be moved into the ion trap 104 by applying an appropriate potential to the ion source 102 and the electrode of the ion trap 104. Ions can also be generated in the ion trap 104, in which case charged particles such as ions (eg, buffer gas ions) and electrons generated by the ion source 102 enter the ion trap 104 and collide with gas particles to be analyzed. In general, ions can be generated at multiple locations simultaneously (eg, both in ion source 102 and ion trap 104), and all generated ions are eventually trapped in ion trap 104. Although the discussion in this section focuses primarily on the direct ion generation from the gas particles of interest within the ion source 102, the aspects and features disclosed herein are other configurations of the analyzer 100. It is also generally applicable to secondary ion generation from gas particles of interest within the element.

  A variety of different spacings can be used between the electrode 210 and the back electrode 220. In general, the efficiency of ion generation includes many potential differences including the potential difference between electrode 210 and electrode 220, the gas pressure within GDI source 200, the distance between electrode 210 and electrode 220, and the chemical structure of the gas particles being ionized. It is determined by the factors. Typically, the distance 234 is relatively small to ensure that the GDI source 200 is compact. In some embodiments, the distance 234 between the electrode 210 and the electrode 220 is 1.5 cm or less (eg, 1 cm or less, 0.75 cm or less, 0.5 cm or less, 0.25 cm or less, 0.1 cm or less).

  The gas pressure in the GDI chamber 230 is generally regulated by the pressure regulation subsystem 120. In some embodiments, the gas pressure in the GDI chamber 230 is generally the same as the gas pressure in the ion trap 104 and / or detector 118. In some embodiments, the gas pressure in GDI chamber 230 is different from the gas pressure in ion trap 104 and / or detector 118. Typically, the gas pressure in the GDI chamber 230 is 100 Torr or less (e.g., 50 Torr or less, 20 Torr or less, 10 Torr or less, 5 Torr or less, 1 Torr or less, 0.5 Torr or less) and / or 100 mTorr or more ( For example, 200 mTorr or more, 300 mTorr or more, 500 mTorr or more, 1 Torr or more, 10 Torr or more, 20 Torr or more).

  In operation, when a voltage difference is applied between the front electrode 210 and the rear electrode 220 by the voltage source 106 under the control of the controller 108, the GDI source 200 generates a self-sustained glow discharge (or plasma). In some embodiments, this voltage difference can be 200V or higher (eg, 300V or higher, 400V or higher, 500V or higher, 600V or higher, 700V or higher, 800V or higher) to maintain glow discharge. As described above, the detector 118 detects ions generated by the GDI source 200 and the potential difference between the electrodes 210 and 220 is adjusted by the controller 108 to determine the rate at which ions are generated by the GDI source 200. Can be controlled.

  In some embodiments, as shown in FIG. 1D, the GDI source 200 is directly attached to the support base 140 and the electrodes 210 and 220 are directly connected to the voltage source 106 via the support base 140. In some embodiments, as shown in FIG. 1E, GDI source 200 is part of module 148 and electrodes 210 and 220 are connected to electrode 142 of support base 148. When module 148 is plugged into support base 140, electrodes 210 and 220 are connected to voltage source 106 via electrode 144 that engages electrode 142.

  By applying a potential of a different polarity to the ground potential established by the voltage source 106. The GDI source 200 can be configured to operate in different ion modes. For example, during typical operation of the GDI source 200, only a fraction of the gas particles are first ionized in the GDI chamber 230 by an irregular process (eg, thermal collision). In some embodiments, a potential is applied to the front electrode 210 and the back electrode 220 such that the front electrode 210 acts as a cathode and the back electrode 220 acts as an anode. In this configuration, positive ions generated in the GDI chamber 230 are moved toward the front electrode 210 by an electric field in the chamber. Negative ions and electrons are moved toward the back electrode 220. These electrons and ions collide with other gas particles to generate a large amount of ions. Negative ions and / or electrons exit the GDI chamber via the back electrode 220.

  In some embodiments, appropriate potentials are applied to the front electrode 210 and the back electrode 220 such that the front electrode 210 acts as an anode and the back electrode 220 acts as a cathode. In this configuration, positively charged ions generated within the GDI source 200 exit the chamber via the back electrode 220. These positively charged ions collide with other gas particles and generate a large amount of ions.

  In some embodiments, the user interface 112 can include control means that allow the user to select any of the above-described ionization modes. The selection of an appropriate ionization mode may depend on the nature of the substance being analyzed by the analyzer 100. Certain materials are more efficiently ionized as positive ions, and the mode of operation can be selected so that the back electrode 220 functions as a cathode. Positive ions generated during operation in this mode exit the GDI chamber 200 via the rear electrode 220. Alternatively, certain materials are more efficiently ionized as negative ions, and the mode of operation can be selected such that the back electrode 220 functions as an anode. Negative ions generated during operation in this mode exit the GDI source 200 via the rear electrode 220. In general, the controller 108 is configured to monitor the ion current measured by the detector 118 and select an appropriate mode of operation of the GDI source based on the ion current. Alternatively or additionally, the user of the analyzer 100 can use the control means displayed on the user interface 114 or enter the appropriate configuration settings into the storage device 114 of the analyzer 100 in the appropriate mode of operation. Can be selected.

  As ions are generated in either mode of operation and exit the GDI chamber 230 via the back electrode 220, these ions enter the ion trap 104 via the end cap electrode 304. In general, the back electrode 220 can include one or more apertures 240. The number of apertures 240 and their cross-sectional shape are generally selected such that a relatively uniform spatial distribution of ions incident on the end cap electrode 304 is achieved. As ions generated in the GDI chamber 230 exit the chamber via one or more apertures 240 in the back electrode 220, they are spatially dispersed from one another by collisions and space charge interactions. As a result, the overall spatial distribution of ions exiting the GDI source 200 is diffused. By selecting the appropriate number of apertures 240 with a particular cross-sectional shape, the spatial distribution of ions exiting the GDI source 200 overlaps or fills all the apertures 292 formed in the end cap electrode 304. Can be controlled. In some embodiments, additional ion optics (eg, an ion lens) can be placed between the back electrode 220 and the end cap electrode 304 to further manipulate the spatial distribution of ions exiting the GDI source 200. However, a unique advantage of the compact ion source disclosed herein is that proper ion distribution is obtained without placing additional elements between the back electrode 220 and the end cap electrode 304.

  In some embodiments, the back electrode 220 includes a single aperture 240. The cross-sectional shape of the aperture 240 may be circular, square, square, or can generally correspond to a polygon having N sides of any regular or irregular shape. In some embodiments, the cross-sectional shape of the aperture 240 may be an irregular shape.

  In some embodiments, the back electrode 220 includes two or more apertures 240. In general, if the back electrode 220 remains mechanically stable enough for use with the GDI source 200, the back electrode 220 can include any number of apertures separated by any distance (e.g., 2 or more, 4 or more, 8 or more, 16 or more, 24 or more, 48 or more, 64 or more, 100 or more, 200 or more, 300 or more, 500 or more). 2C-2H show various embodiments of the back electrode 220, each with a variety of different apertures 240. FIG. As shown in FIGS. 2C-2H, the back electrode 220 can be generally circular, square, or any other shape.

  FIG. 2C shows the back electrode 220 with a regular array of apertures 242. Although 25 apertures 242 are shown in FIG. 2C, more generally there can be any number of apertures 242. Furthermore, although the aperture 242 has a circular cross-sectional shape, more generally, an aperture 242 with any regular or irregular cross-sectional shape can be used. Apertures with different cross-sectional shapes may be used with one electrode 220. In general, the size of the opening formed by the aperture 242 may be selected as desired, and different size apertures 242 may be present in a single rear electrode 220. Typically, the number of apertures formed in the back electrode 220 and the size of the aperture control the gas pressure drop of the electrode. Therefore, by selecting the aperture size and number, the target pressure drop of the rear electrode 220 during the operation of the mass spectrometer 100 can be achieved.

  2D-2G illustrate a further exemplary embodiment of the back electrode 220 with openings 243, 244, 245, and 246. In FIGS. 2D-2G, the openings 243, 244, 245, and 246 may be formed by slits (eg, continuous openings) or a series of apertures formed in the back electrode 220 and spaced from one another. As shown in FIGS. 2D-2G, the openings 243, 244, 245, and 246 can be arranged to form an array of linear openings, an array of concentric arcs, a serpentine path, and a spiral path. However, the embodiment shown in FIGS. 2D-2G is for illustration purposes only. More generally, a wide variety of different arrangements of apertures with different cross-sectional shapes and sizes can be used with the back electrode 220.

  FIG. 2H shows one embodiment of the back electrode 220 with a hexagonal array of apertures 247. The hexagonal arrangement shown in FIG. 2H and the square or quadrangular arrangement shown in FIG. 2C are examples of regular arrangements of apertures that can be formed in the rear electrode 220. More generally, however, the rear electrode 220 may use a variety of different regular array apertures, such as but not limited to a circular array or a radial array.

  As shown in FIGS. 2A and 2B, the end cap electrode 304 of the ion trap 104 may also include one or more apertures 294. In some embodiments, the end cap electrode 304 includes a single aperture 294 with a circular, square, rectangular, or other polygonal cross-sectional shape with N sides. In some embodiments, the aperture has an irregular cross-sectional shape.

  More generally, the end cap electrode 304 can include a number of apertures 294. The types of apertures in the end cap electrode 304, their arrangement, and the criteria for selecting a particular type of aperture are generally similar to the types, arrangements, and criteria already described in connection with the back electrode 220. Further, the above description applies to the aperture 294 formed in the end cap electrode 304 as well.

  As shown in FIGS. 2A and 2B, the back electrode 220 is spaced from the end cap electrode 304 by an amount 244. Due to the space between these electrodes, ions exiting from the rear electrode 220 are spatially dispersed, and the aperture 294 formed in the end cap electrode 304 can be filled as uniformly as possible. In order to further facilitate uniform filling of the apertures 294, in some embodiments, the pattern of the apertures 240 formed in the back electrode 220 can be matched to the pattern of the apertures 294 formed in the end cap electrode 304. .

  More specifically, as shown in FIG. 2H, the pattern of the aperture 247 formed in the rear electrode 220 defines the cross-sectional shape of the rear electrode 220. Similarly, the aperture pattern formed in the end cap electrode 304 defines the cross-sectional shape of the end cap electrode 304. In some embodiments, the cross-sectional shapes of the rear electrode 220 and the end cap electrode 304 are generally coincident. As used herein, “substantially match” means that the relative position of at least 70% or more of the aperture formed in the rear electrode 220 is the same as the relative position of the aperture formed in the end cap electrode 304. . For each aperture, its position corresponds to the position of the center of its mass.

  In some embodiments, the pattern of apertures 240 formed in the back electrode 220 exactly matches the pattern of apertures 294 formed in the end cap electrode 304, i.e., there is a one-to-one relationship between these apertures. There is a corresponding relationship. In general, as the degree to which these apertures match at the rear electrode 220 and the end cap electrode 304 increases, the ions from the rear electrode 220 fill the aperture 294 of the end cap electrode 304 more evenly. The distance 244 from the end cap electrode 304 can be shortened. If the apertures between these electrodes are perfectly or nearly perfectly matched, the distance 244 is zero (i.e., the rear electrode 220 can be placed directly adjacent to the end cap electrode 304), making the GDI source 200 extremely compact Can be. Further, as the degree of matching between the apertures increases, the number of ions entering the aperture 294 can be maximized by reducing the number of ions that impinge on the portion of the end cap electrode 304 between the apertures. As a result, the ion collection efficiency of the ion trap 104 is improved. In addition, by improving the efficiency with which ions generated by the ion source 102 are collected within the ion trap 104, the overall size of the back electrode 220 and end cap electrode 304 can be matched to one electrode and / or aperture. It can be reduced compared to an electrode with no aperture.

  In some embodiments, the back electrode 220 and the end cap electrode 304 can be formed as a single element, and ions generated by the GDI source 200 can enter the ion trap 104 directly through the element. In such embodiments, the integrated back and end cap electrodes can include a single aperture or multiple apertures as described above.

  Further, in some embodiments, the end cap electrodes of the ion trap 104 can function as the front electrode 210 and the back electrode 220 of the GDI source 200. As will be described in detail later, the ion trap 104 includes two end cap electrodes 304 and 306 disposed on opposite surfaces of the trap. By applying an appropriate potential (eg, as described above with respect to the front electrode 210 and the back electrode 220) to these electrodes, the end cap electrode 304 can function as the front electrode 210 and the end cap electrode 306 can be the back electrode. Can function as 220. Accordingly, in these embodiments, the ion trap 104 also functions as the glow discharge ion source 102.

  Charge particles can be generated by the GDI source 200 using various modes of operation. For example, in some embodiments, a continuous mode of operation can be used. FIG. 2I includes a graph illustrating one embodiment of a continuous mode of operation in which a constant bias voltage 262 is applied between the front electrode 210 and the rear electrode 220 of the GDI source 200. In this mode, charged particles are continuously generated in the ion source.

  In some embodiments, GDI source 200 is configured for pulsed operation. FIG. 2I illustrates one embodiment of a pulse mode operation in which a bias potential 272 is applied to the front electrode 210 and the rear electrode 220 over a period of time 272. By repeatedly applying the bias potential 272, the number of repetitions of the pulse operation corresponding to the reverse of the period 276 between successive pulses is defined. In general, the period 276 may be significantly longer (eg, 100 times longer) than the period 274 during which the bias potential 272 is applied to the electrodes. In some embodiments, for example, period 274 is about 0.1 milliseconds and period 276 is about 10 milliseconds. More generally, the period 274 is 5 milliseconds or less (e.g., 4 milliseconds or less, 3 milliseconds or less, 2 milliseconds or less, 1 millisecond or less, 0.8 milliseconds or less, 0.6 milliseconds or less, 0.5 milliseconds or less) 0.4 ms or less, 0.3 ms or less, 0.2 ms or less, 0.1 ms or less, 0.05 ms or less, 0.03 ms or less), and the period 276 is 50 ms or less (for example, 40 ms or less, 30 Msec or less, 20 msec or less, 10 msec or less, 5 msec or less).

  Ions are generated over a period 274 in which a bias potential 272 is applied to the electrode. In some embodiments, as described in detail below, the timing of the pulse bias potential 272 during pulse mode operation is used to generate a high voltage RF signal 482 that is applied to the center electrode of the ion trap 104. It can also be synchronized with the modulation signal 412. Graph 280 in FIG. 2J is a plot of modulation signal 412 used to generate RF signal 482 applied to the center electrode of ion trap 104. Comparing the graph 280 with the graph 270, when the pulse bias potential 272 is applied to the electrode of the GDI source 200, the modulation signal 412 is stopped. During this period, ions are generated at the GDI source 200. Next, the bias potential 272 is stopped and the modulation potential 282 is applied. At interval 284, these ions are trapped and stabilized in ion trap 104. Then, at the interval 286, the trapped ions are ejected from the ion trap 104 into the detector 118 by increasing the amplitude of the potential applied to the center electrode of the ion trap 104.

  Pulse mode operation has several advantages. For example, the number and duration and / or amplitude of the pulse bias potential 272 can be adapted to the amount of gas particles to be analyzed and the gas pressure present in the ion trap 104. In general, the controller 108 monitors the ion current measured by the detector 118, and the controller 108 can adjust one or more of the parameters associated with pulse mode operation based on the magnitude of this ion current.

  In some embodiments, for example, the controller 108 can adjust the amplitude of the bias potential 272. Increasing the bias potential can increase the rate at which ions are generated in the GDI source 200.

  In some embodiments, the controller 108 can adjust the number of repetitions of the bias potential 272. For some analytes of interest, increasing the number of repetitions can increase the rate of ion generation at the GDI source 200. For other analytes, decreasing the number of repetitions can increase the rate of ion generation at the GDI source 200. The controller 108 can be configured to adjust the number of iterations in an adaptive manner until the ion generation rate at the GDI source 200 reaches an appropriate value.

  In some embodiments, the controller 108 can be configured to adjust the duty cycle of the GDI source 200. Referring to the graph 270, the duty cycle of the GDI source 200 shows the ratio of the period 274 during which the bias potential 272 is applied to the total period 276. The controller 108 can be configured to adjust the duty cycle of the GDI source 200. For example, this duty cycle can be reduced to reduce the rate at which ions are generated in the GDI source 200. By reducing the rate at which ions are generated, the signal-to-noise ratio of the measured ion signal is improved and unwanted ghost peaks are removed (if stopped when measured by the ion source 200, the GDI source 200 Peaks due to unwanted charged particles generated by: Alternatively, the duty cycle can be increased to increase the rate at which ions are generated at the GDI source 200.

  In some embodiments, the controller 108 has a duty between 1% and 50% (e.g., between 1% and 40%, between 1% and 30%, between 1% and 20%, It can be configured to adjust to a value between 1% and 10%).

  Another important advantage of pulse mode operation is that the bias potential applied between the electrodes 210 and 220 is turned off when not needed, for example when the ion source 200 has already generated ions. Stopping the bias potential during most of the duty cycle of the ion source 200 can lead to a significant reduction in the amount of power required to operate the analyzer.

  Furthermore, pulse mode operation avoids the use of a gate or shield placed between the GDI source 200 and the detector 118. By eliminating the gates and shields commonly used in conventional mass spectrometers, considerable space is saved and the amount of power required to operate the analyzer 100 is reduced.

  In some embodiments, the operating conditions of the GDI source 200 can be checked using an automatic calibration procedure. For example, the user can initiate a calibration procedure that sequentially analyzes one or more known reference samples. A phantom peak (ie, a peak that should not be present in the measured spectrum) may indicate that the GDI source 200 is contaminated. For example, one of the electrodes 210 and 220 may be embedded with sticky particles or debris that can cause phantom peak detection. In some configuration procedures, the sample is not injected and phantom peaks are detected against the background of analyzer noise. The determination of whether the GDI source 200 needs to be replaced may be based on the result of calibration, for example, the number and size of detected phantom peaks.

  To facilitate replacement, in some embodiments, the ion source 200 can be configured as a separate module from the other components of the analyzer 100. For example, as shown in FIG. 2B, the GDI source 200 can be implemented as a separate module that can be easily removed from other components of the analyzer 100 or by releasing the mounting element 250 from the housing 122. Alternatively, the electrodes 210 and 220 can be configured to be individually removable from the GDI source 200. Removal of the electrodes 210 and 220 can be accomplished, for example, by removing a cover that is integral with the housing 122 adjacent to the location of the electrodes. When this cover is removed from the housing 122, the exposed electrodes are removable from the GDI source 200.

  In some embodiments, the GDI source 200 can be cleaned instead of being replaced. For example, the GDI source 200 can be cleaned by applying a potential bias corresponding to the reverse duty cycle to the electrodes 210 and 220. FIG. 2J is a graph 263 of the reverse duty cycle applied to the electrodes 210 and 220 during the cleaning process, with the bias potential 264, ie reversed with respect to the pulse mode bias potential shown in the graph 270. A constant DC potential is applied during most of the duty cycle and is interrupted only by a short potential drop in period 274. These potential drops are repeated in period 276. Without wishing to be bound by theory, it is believed that this fast voltage change facilitates the removal of the sticky particles embedded in electrodes 210 and 220. Once it is determined that the GDI source 200 is clean (eg, using the calibration procedure described above), the GDI source 200 can be switched to normal operation (eg, pulse mode operation) to generate ions.

  In some embodiments, the controller 108 has a duty cycle during cleaning between 50% and 100% (e.g., between 50% and 90%, between 50% and 80%, 50% and 70%). It is configured to adjust to a value between% and between 50% and 60%. Reverse duty cycle spans a total period of 5 seconds or more (for example, 10 seconds or more, 20 seconds or more, 30 seconds or more, 40 seconds or more, 50 seconds or more, 1 minute or more, 2 minutes or more, 3 minutes or more, 5 minutes or more) Can be applied.

  If the electrodes of the GDI source 200 are contaminated, other methods can be used to clean them. In some embodiments, clean gas may be injected into the GDI source 200 to facilitate removal of the sticky particles of the electrodes 210 and 220. Suitable clean gases can include, for example, noble gases. Further, in some embodiments, cleaning the electrodes of the GDI source 200 can also be facilitated by heating the electrodes 210 and 220. In some embodiments, the electrodes 210 and 220 can be removed from the GDI source 200 and cleaned in a suitable cleaning solution.

  The above description focuses on the measurement of phantom peaks to determine whether the GDI source 200 is contaminated. More generally, other methods can be used in addition to or instead of phantom peak detection. For example, the controller 108 can be configured to monitor the measurement of ion current by the detector 118. If the ion signal measured by the detector 118 fluctuates or suddenly changes (eg, jumps up or down) above a threshold amount, or the average detected ion / electron signal has an attenuation below a certain threshold If so, the controller 108 can automatically determine that cleaning or replacement of the GDI source 200 is desired.

  Various materials can be used to form the electrodes of the ion source 102, including the electrodes 210 and 220 of the GDI source 200. In some embodiments, the electrodes of the ion source 102 can be made from materials such as copper, aluminum, silver, nickel, gold, and / or stainless steel. In general, materials that are less susceptible to sticky particle adsorption are advantageous because such materials typically do not require frequent cleaning or replacement.

  The above description has focused on the use of the GDI source 200 in the analyzer 100. However, the features, design criteria, algorithms, and aspects described above apply equally to other types of ion sources that can be used with analyzer 100, such as capacitor discharge sources and thermionic emission sources. In particular, the capacitor discharge source is well suited for use at relatively high gas pressures where the analyzer 100 operates. Accordingly, the above description applies to such ion sources. For example, FIG. 2K shows an example of a capacitor discharge source 265 that includes an array of ionization sources 266. The inset of FIG. 2K shows an enlarged view of a single ionization source 266 with electrical wires 267 and insulated wires 268. When a bias potential is applied to line 267 by voltage source 106, a plasma discharge is generated from each ionization source 266. Ions generated by the condenser discharge source 265 enter the ion trap 104 where they are captured and selectively ejected for detection. Additional aspects and features of capacitor discharge sources are described, for example, in US Pat. No. 7,274,015, the entire contents of which are incorporated herein by reference.

  Due to the use of compact and closely spaced electrodes, the overall size of the ion source 102 can be reduced. The maximum dimension of the ion source 102 refers to the maximum linear distance between any two points of the ion source. In some embodiments, the maximum dimension of the ion source 102 is 8.0 cm or less (eg, 6.0 cm or less, 5.0 cm or less, 4.0 cm or less, 3.0 cm or less, 2.0 cm or less, 1.0 cm or less).

III. As described in Section I of the Ion Trap , the ions generated by the ion source 102 are trapped in the ion trap 104, where the ions are subjected to an electric field formed by applying a potential to the electrode of the ion trap 104. Circulate under influence. Such a potential is applied to the electrode of the ion trap 104 by the voltage source 106 after receiving a control signal from the controller 108. Controller 108 sends a signal to voltage source 106 to eject circulating ions from ion trap 104 for detection, which modulates the amplitude of the radio frequency (RF) electric field in ion trap 104. Let Due to the modulation of the RF electric field amplitude, circulating ions in the ion trap 104 deviate from the trajectory, exit the ion trap 104 and enter the detector 118 where they are detected.

  As described in Section I, to ensure that the mass spectrometer 100 is compact and consumes a relatively small amount of power during operation, the mass spectrometer 100 is a single compact device within the pressure regulation subsystem 120. The internal gas pressure is adjusted using only a mechanical pump. As a result, the mass spectrometer 100 operates at an internal gas pressure that is higher than the internal pressure of a conventional mass spectrometer. In order to ensure that gas particles drawn into the analyzer 100 are rapidly ionized and analyzed, the internal volume of the mass spectrometer 100 is significantly smaller than the internal volume of a conventional mass spectrometer. By reducing the internal volume of the analyzer 100, the pressure regulation subsystem 120 can quickly draw gas particles into the analyzer 100. Furthermore, by ensuring rapid ionization and analysis, the user of the analyzer 100 can quickly obtain information about a particular substance. The small internal volume of the analyzer 100 also provides the added benefit of reducing the internal surface that is susceptible to contamination during operation. Conventional mass spectrometers use a variety of different mass analyzers, many of which have a large internal volume that is maintained at a low pressure during operation and / or consume a large amount of power during operation. For example, some mass spectrometers use linear quadrupole mass filters, but they extend in the axial direction and thus have a large internal volume, which allows mass filtering and large charge storage capacity. Some mass spectrometers use magnetic sector mass filters, which are typically large and generate a mass filtering magnetic field, which can consume a large amount of power. Conventional mass spectrometers can also use hyperbolic ion traps, which can have a large internal volume and can be difficult to manufacture.

  In contrast to the conventional ion trap technology described above, the mass spectrometer disclosed herein uses a compact, cylindrical ion trap to capture and analyze ions. FIG. 3A is a cross-sectional view of one embodiment of the ion trap 104. The ion trap 104 includes a cylindrical center electrode 302, two end cap electrodes 304 and 306, and two insulating spacers 308 and 310. The electrodes 302, 304, and 306 are connected to the voltage source 106 via control lines 312, 314, and 316, respectively. The voltage source 106 is connected to the controller 108 via the control line 120e, and the controller 108 transmits a signal via the control line 127e to instruct the voltage source 106 to apply a potential to the electrode of the ion trap 104.

  In operation, ions generated by the ion source 102 enter the ion trap 104 through the aperture 320 in the electrode 304. The voltage source 106 applies a potential to the electrodes 304 and 306 to generate an axial electric field (eg, symmetrical about the axis 318) within the ion trap 104. This axial electric field confines ions in the axial direction between the electrodes 304 and 306, ensuring that the ions do not exit the ion trap through the aperture 320 or aperture 322 of the electrode 306. The voltage source 106 also applies a potential to the central electrode 302 to generate a radial confinement electric field in the ion trap 104. This radial electric field confines ions radially within the internal aperture of electrode 302.

  The presence of an axial electric field and a radial electric field in the ion trap 104 causes ions to circulate within the trap. The trajectory shape of each ion is determined by many factors including the geometry of the electrodes 302, 304, and 306, the magnitude and sign of the potential applied to the electrode, and the mass-to-charge ratio of the ion. By changing the magnitude of the potential applied to the central electrode 302, ions of a specific mass to charge ratio deviate from the trajectory in the trap 104, exit the trap via the electrode 306, and enter the detector 118. Thus, to selectively analyze ions with different mass to charge ratios, the voltage source 106 changes the amplitude of the potential applied to the electrode 302 in steps (under the control of the controller 108). When the amplitude of the electric field changes, ions with different mass to charge ratios are ejected from the ion trap 104 and detected by the detector 118.

  The electrodes 302, 304, and 306 of the ion trap 104 are generally formed of a conductive material such as stainless steel, aluminum, or other metal. The spacers 308 and 310 are generally formed from ceramics, Teflon (eg, fluorinated polymer coating material), rubber, or various plastic materials.

The end cap electrodes 304 and 306, the central electrode 302, and the central openings of the spacers 308 and 310 can have the same diameter and / or shape, or different diameters and / or shapes. For example, in the embodiment shown in FIG. 3A, the central opening of electrode 302 and spacers 308 and 310 has a circular cross-sectional shape and diameter c ₀ , and end cap electrodes 304 and 306 have a circular cross-sectional shape and diameter c _2. A central opening with <c ₀ is provided. As shown in FIG. 3A, the electrode and spacer openings are axially aligned along the axis 318, and when the electrodes and spacers are assembled in a sandwich structure, the electrode and spacer openings are within the ion trap 104. A continuous axial opening is formed that extends.

In general, the diameter c ₀ of the central opening of electrode 302 is selected as desired to achieve a specific target resolution when selectively ejecting ions from ion trap 104 and to adjust the total internal volume of analyzer 100 do it. In some embodiments, c ₀ is approximately 0.6 mm or greater (eg, 0.8 mm or greater, 1.0 mm or greater, 1.2 mm or greater, 1.4 mm or greater, 1.6 mm or greater, 1.8 mm or greater). Diameter c ₂ of the central opening of the end cap electrodes 304 and 306 is also to achieve a specific goal resolution when ejecting ions from the ion trap 104, and selects as desired to ensure proper containment of not ejected ions May be. In some embodiments, c ₂ is approximately 0.25 mm or greater (eg, 0.35 mm or greater, 0.45 mm or greater, 0.55 mm or greater, 0.65 mm or greater, 0.75 mm or greater).

The axial length c ₁ of the combined opening of electrode 302 and spacers 308 and 310 is also desirable to ensure proper ion confinement and to achieve a specific target resolution when ions are ejected from ion trap 104. You can choose as you please. In some embodiments, c ₁ is approximately 0.6 mm or greater (eg, 0.8 mm or greater, 1.0 mm or greater, 1.2 mm or greater, 1.4 mm or greater, 1.6 mm or greater, 1.8 mm or greater).

Experiments have confirmed that when c ₀ and c ₁ are selected such that c ₁ / c ₀ exceeds 0.83, the resolution of the analyzer 100 increases. Thus, in some embodiments, c ₀ and c ₁ are such that the value of c ₁ / c ₀ is 0.8 or greater (eg, 0.9 or greater, 1.0 or greater, 1.1 or greater, 1.2 or greater, 1.4 or greater, 1.6 or greater). Selected.

  Due to the relatively small size of the ion trap 104, the number of ions that can be simultaneously trapped in the ion trap 104 is limited by various factors. One such factor is the space charge interaction between ions. As the density of trapped ions increases, the average spacing between trapped circulating ions decreases. As these ions (all with positive or negative charges) are brought closer together, the repulsion between these trapped ions increases.

  In order to overcome the limitation of the number of ions that can be simultaneously trapped in the ion trap 104 and to increase the capacity of the analyzer 100, in some embodiments, the analyzer 100 may include an ion trap with multiple chambers. it can. FIG. 3B shows a schematic diagram of an ion trap 104 with a plurality of ion chambers 330 arranged in a hexagonal array. Each chamber 330 functions similarly to the ion trap 104 of FIG. 3A and includes two end cap electrodes and a cylindrical center electrode. In FIG. 3B, end cap electrode 304 is shown with a portion of end cap electrode 306. The end cap electrode 304 is connected to the voltage source 106 via a connection point 344, and the end cap electrode 306 is connected to the voltage source 106 via a connection point 332.

  FIG. 3C is a cross-sectional view taken along a cross-sectional line AA in FIG. 3B. Each of the five ion chambers 330 along the section line AA is shown. The voltage source 106 is connected to the central electrode 302 via a single connection point (not shown in FIG. 3C). As a result, by applying an appropriate potential to the electrode 302, the voltage source 106 (under the control of the controller 108) simultaneously captures ions in each chamber 330 and delivers ions with a selected mass to charge ratio to each. The chamber 330 can be discharged.

  In some embodiments, the number of ion chambers 330 in the ion trap 104 can match the number of apertures formed in the end cap electrode 304. As described in Section II, the end cap electrode 304 can generally include one or more apertures. When the end cap electrode 304 includes a plurality of apertures, the ion trap 104 also includes a plurality of ion chambers 330, with each aperture formed in the end cap electrode 304 corresponding to a different ion chamber 330. In this manner, ions generated in the ion source 102 can be efficiently collected by the ion trap 104 and captured in the ion chamber 330. As described above, the use of multiple chambers reduces the space charge interaction between trapped ions and increases the trapping capability of the ion trap 104. In general, the position and cross-sectional shape of the ion chamber 330 may be the same as the arrangement and shape of the apertures 240 and 294 described in Section II.

  As an example, referring to FIG. 3B, the end cap electrode 304 includes a plurality of apertures arranged in a hexagonal array. Each aperture formed in electrode 304 corresponds to a corresponding ion chamber 330, and thus ion chambers 330 are also arranged in a hexagonal array.

  In some embodiments, the number, arrangement, and / or cross-sectional shape of the ion chamber 330 does not match the arrangement of the openings in the end cap electrode 304. For example, the end cap electrode 304 includes only one or a few apertures 294, but the ion trap 304 can include a plurality of ion chambers 330. The use of multiple ion chambers increases the capture capability of the ion trap 104, so using multiple ion chambers is advantageous even if the ion chamber placement is not consistent with the end cap electrode 304 aperture placement. It can be.

  Additional side features of the ion trap 104 are described in US Pat. No. 6,469,298, US Pat. No. 6,762,406, and US Pat. No. 6,933,498, the entire contents of each of which are incorporated herein by reference.

IV. Voltage Source The voltage source 106 provides operating power and potential to the components of the analyzer 100 based on signals transmitted by the controller 108 via the control line 127e. As discussed above in Section I, the key advantages of the mass spectrometer disclosed herein are its compact size and significantly lower power consumption compared to conventional mass spectrometers. The analyzer 100 can generally operate using a variety of voltage sources, but it is advantageous if the voltage source 106 is highly efficient in order to reduce the power consumption of the analyzer 100 as much as possible.

  However, highly efficient voltage sources that are small in size and generate sufficient voltage to drive the components of analyzer 100 are not readily available commercially. FIG. 4A shows a schematic diagram of one embodiment of a high efficiency voltage source 106 configured to provide a high voltage RF signal 482 that is applied to the central electrode 302 of the ion trap 104. In operation, the voltage source 106 can amplify the voltage received from the power supply 440 while modifying the waveform of the high voltage RF signal 482 to suit a particular mass spectrum measurement.

  The design of the power supply 106 allows the analyzer 100 to operate with high power efficiency during various sweep stages of the high voltage RF signal 482. At each stage, power efficiency is defined as the ratio of input power to output power. In some embodiments, the efficiency of the power source 106 is 40% or higher (e.g., 50% or higher, 60% or higher, 70% or higher, 80% or higher, 90% or higher) at all stages of voltage amplification. Can do. In contrast, conventional power amplifiers (eg, emitter followers or class A amplifiers) typically have maximum efficiency at the highest amplification level, but are much less efficient at lower amplification levels. Thus, conventional power amplifiers are inadequate and may not be sufficient for applications that require sweep voltage amplification.

  In addition to high efficiency operation, the voltage source 106 allows a relatively low power source (eg, a battery) to provide the power and potential necessary to operate the various components of the analyzer 100. As a result, the analyzer 100 has a compact form factor and is significantly lighter than conventional power amplifiers.

  Referring to FIG. 4A, voltage source 106 includes a proportional-integral-derivative (PID) control loop 420, a switch mode power supply 430, an optional linear regulator 450, a class D amplifier 460, and a resonant circuit 480. In some embodiments, the various components of the voltage source 106 can be integrated into a module that can be plugged into the support base 140. This allows the voltage source 106 to be easily replaced with another module if it fails. Alternatively, in some embodiments, one or more components of voltage source 106 can be implemented as separate modules and can be interchanged by themselves. In some embodiments, some or all components can be attached directly to the support base 140. Since each component shown in FIG. 4A is commonly commercially available at a relatively low cost, the voltage source 106 can be made economically.

  In operation, the PID control loop 420 receives the modulation signal 412 from the modulation signal generator 410, which may or may not be a component of the voltage source 106. FIG. 4B shows an example of a modulated signal 412 where the change in signal amplitude (ie, the envelope) is shown as a function of time. The envelope of the modulated signal 412 is generally correlated with the envelope of the output high voltage RF signal 482. Based on modulated signal 412, PID control loop 420 sends control signals 422 and 422 to switch mode power supply 430 and linear regulator 450 (if present), respectively.

  The switch mode power supply 430 is configured to receive an input power signal 442 from a power supply 440 that can include a battery (eg, lithium ion, lithium polymer, nickel cadmium, nickel metal hydride battery). The voltage supplied by power supply 440 is typically between about 0.5V and about 13V. As an example, this voltage is about 7.2V. Switch mode power supply 430 amplifies input power signal 422 based on control signal 422 to provide modulated voltage signal 432 that is transmitted to linear regulator 450 (if present). The modulated voltage signal 432 is shown in FIG. 4C. The modulated voltage signal 432 typically has an amplitude between 0V and about 25V.

  In some embodiments, the switch mode power supply 430 includes a switching regulator for efficient power amplification. In operation, the input power signal 422 may be lower, the same or higher than the output voltage signal 432. This feature is advantageous when the power source 440 is a battery. Unlike linear power supplies, switch mode power supplies 430 (which are non-linear amplifiers) provide high power conversion because they lose little or no power when switching between various amplification states. In addition, the switch mode power supply 430 is typically compact and lightweight with conventional power amplifiers due to the size and weight of the smaller internal transformer.

  A linear regulator 450 is optionally included in the voltage source 106. If the linear regulator 150 is not present in the voltage source 106, the modified voltage signal 432 is sent directly from the switch mode power supply 430 to the class D amplifier 460. Alternatively, if linear regulator 450 is present at voltage source 106, linear regulator 450 receives both modulated voltage signal 432 from switch mode power supply 430 and control signal 424 from PID control loop 420. .

  The linear regulator 450 serves to filter irregularities in the corrected voltage signal 432. Filtered voltage signal 442 from linear regulator 450 is received by class D amplifier 460. Typically, linear regulator 450 is a low dropout voltage regulator, where a constant low drop voltage ensures that the overall efficiency of voltage source 106 is only slightly reduced by the presence of linear regulator 450. . In some embodiments, the control signal 422 received by the linear regulator 450 is used to modify the envelope of the output voltage signal 442 to be suitable for mass spectral measurements of a particular material.

  A reference wave generator 470 is optionally included in the voltage source 106. If provided, reference wave generator 470 provides reference wave signal 472 to class D amplifier 460. In general, the reference wave signal 472 has a frequency in a high frequency range (for example, from about 0.1 MHz to about 50 MHz). For example, in some embodiments, the reference signal 472 can comprise a frequency of 1 MHz or higher (eg, 2 MHz or higher, 4 MHz or higher, 6 MHz or higher, 8 MHz or higher, 15 MHz or higher, 30 MHz or higher).

  FIG. 4D shows an example of the reference wave signal 472. In FIG. 4D, an example of the reference wave signal 472 is a square wave. More generally, the reference wave generator 470 can generate a reference wave signal 472 of a variety of different waveforms. In some embodiments, for example, the reference wave signal 472 can match either a triangular waveform, a sine waveform, or a waveform close to a sine wave.

  The class D amplifier 460 is a reference wave signal 472 (if a reference wave generator 470 is provided) and a filtered voltage signal 442 (or a modified voltage signal 432 if a linear regulator 450 is not provided). Both are received and a modulated RF signal 462 is generated from these input signals. FIG. 4E shows an example of the modulated RF signal 462. In this example, the period of signal 462 is approximately 10 milliseconds. The amplitude of signal 462 varies between about 0V and about 30V. The frequency of the carrier wave of the RF signal 462 is the same as or substantially the same as the frequency of the reference wave signal 472. The envelope of the RF signal 462 (eg, indicated by the dashed line in FIG. 4E) is the same as or approximately the same as the envelope of the filtered voltage signal 442 (or modified voltage signal 432).

  FIG. 4F is a schematic diagram of one embodiment of a class D amplifier 460. Class D amplifier 460 includes a pair of transistors 441. Within class D amplifier 460, reference wave signal 472 is modulated by the envelope of filtered voltage signal 442 (or modified voltage signal 432) to generate RF signal 462.

  The RF signal 462 is received by a resonant circuit 480, which is also schematically shown in FIG. 4F. The resonant circuit 480 includes an inductor 486 and a capacitor 488. In some embodiments, the position of inductor 486 and capacitor 488 may be interchanged with respect to the position shown in FIG. 4F. The values of the inductance of inductor 486 and the capacitance of capacitor 488 are generally selected such that the resonant frequency of circuit 480 substantially matches the frequency of reference wave signal 472.

  In some embodiments, the resonant circuit 480 comprises a Q factor of 60 or greater (eg, 80 or greater, 100 or greater). When the RF signal 462 is applied to the resonant circuit 480, a high voltage RF signal 482 is generated at the capacitor 488. In general, the waveform of the high voltage RF signal 482 is the same as or approximately the same as the waveform of the RF signal 462 except that the amplitude of the high voltage RF signal 482 is significantly greater than the amplitude of the RF signal 462. For example, in some embodiments, the maximum amplitude of the high voltage RF signal 482 is 100V or greater (eg, 500V or greater, 1000V or greater, 1500V or greater, 2000V or greater). In general, the high Q factor of the resonant circuit 480 generates a large amplitude voltage in the RF signal 462.

  The combination of class D amplifier 460 and resonant circuit 480 is advantageous for a number of reasons including low power consumption and frequency regulation. A further important advantage stems from the fact that a pure sinusoidal reference signal 472 is not required for operation. Actually, the combination of the class D amplifier 460 and the resonance circuit 480 can use reference wave signals having various waveform shapes. A constant waveform shape such as a square wave can often be generated with higher fidelity than a pure sinusoidal waveform. As a result, the combination of the class D amplifier 460 and the resonance circuit 480 enables an operation with a highly stable reference wave signal.

  Returning to FIG. 4A, the high voltage RF signal 482 can be monitored by a signal monitor 490 that is optional and may or may not be provided to the voltage source 106. The signal monitor 490 receives a feedback signal 484, typically a low amplitude replica of the high voltage RF signal 482, from the resonant circuit 480. Although the feedback signal 484 is typically much smaller in amplitude than the high voltage RF signal 482, the amplitude of the feedback signal 484 is generally proportional in all respects to the amplitude of the high voltage RF signal 482.

  The feedback signal received from the resonant circuit by the signal monitor 490 can be transmitted to the PID control loop 420 and / or the reference wave generator 470 as the control signal 492. Based on modulated signal 492, PID control loop 420 can send modified control signals 422 and 422 to switch mode power supply 430 and linear regulator 450, respectively, to optimize the waveform and amplitude of high voltage RF signal 482. For example, the PID control loop 420 can modify the envelope of the modified voltage signal 432 based on the control signal 492 to maximize the amplitude of the high voltage RF signal 482.

  In some embodiments, the resonant frequency of the resonant circuit 480 may not exactly match the frequency of the reference wave signal 472. For example, this may be due to inaccurate values of the inductance of inductor 486 and / or the capacitance of capacitor 488. Further, the inductance of inductor 486 and / or the capacitance of capacitor 488 may change over time. This may occur, for example, because the class D amplifier 460 distorts the output frequency of the RF signal 462 and the frequency of the RF signal 462 does not match the reference signal wave 472. This mismatch may reduce the efficiency of the power supply 106 because the resonant circuit 480 is not an effective resonator for the RF signal 462.

  Several techniques can be implemented to compensate for this discrepancy. In some embodiments, the frequency of the reference signal 472 can be scanned by the reference generator 470 and the control signal 492 can be monitored at the same time. The reference wave generator 470 can select the optimum frequency of the reference wave signal 472 as the frequency that maximizes the amplitude of the control signal 492.

  In some embodiments, the capacitance of capacitor 488 can be varied in resonant circuit 480 to determine which capacitance value maximizes the amplitude of control signal 492. For this purpose, the capacitor 488 can be a variable capacitor.

  The above-described techniques for compensating for frequency mismatch may be implemented directly in hardware, software, or both. For example, the controller 108 can be configured to perform one or more of these methods to compensate for frequency mismatch. The controller 108 can be configured to perform these methods continuously, automatically and / or to continuously optimize frequency matching. Alternatively, the controller 108 can be configured to execute these methods only upon receiving an instruction from the user, for example, when the user activates the control means of the user interface 112. The techniques for compensating for frequency mismatch disclosed herein are typically completed within 5 minutes (e.g., within 3 minutes, within 2 minutes, within 1 minute) when performed by controller 108. To do.

  A high voltage RF signal 482 is applied to the ion trap 104 (eg, to the central electrode 302 of the ion trap 104) to selectively eject trapped ions for detection by the detector 118. The range of mass to charge ratios that can be analyzed using the ion trap 104 depends on the profile (eg, envelope and maximum amplitude) of the RF signal 462 in addition to other factors. By varying these characteristics of the RF signal 482, the voltage source 106 can select a range of mass to charge ratios to be analyzed (under the control of the controller 108).

  In some embodiments, the voltage source 106 can include multiple reference wave generators 470 and / or multiple resonant circuits 480. In operation, the controller in combination with a specific reference generator 470 and a specific resonant circuit 480 generates a high voltage RF signal 482 suitable for analyzing a specific range of mass to charge ratios using the ion trap 104. 108 can be selected. To change the range of mass to charge ratios to be analyzed, the controller 108 selects a different reference wave generator 470 and / or resonant circuit 480.

V. Detector Detector 118 is configured to detect charged particles that exit ion trap 104. These charged particles may be positive ions, negative ions, electrons, or combinations thereof.

  A wide variety of different detectors can be used with the analyzer 100. FIG. 5A shows one embodiment of a detector 118 that includes a Faraday cup 500. The Faraday cup 500 includes a circular base 502 and a cylindrical side wall 504. In general, the shape and dimensions of the Faraday cup 500 can be varied to optimize the sensitivity and resolution of the analyzer 100.

  For example, the base 502 can comprise a variety of cross-sectional shapes including squares, rectangles, ellipses, circles, or any other regular or irregular shape. The base 502 can be flat or curved, for example.

  FIG. 5B shows a side view of the Faraday cup 500. In some embodiments, the length 506 of the sidewall 504 is 20 mm or less (eg, 10 mm or less, 5 mm or less, 2 mm or less, 1 mm or less, or even 0 mm). In general, the length 506 can be selected according to various criteria including maintaining the compactness of the analyzer 100, providing the necessary selectivity when detecting charged particles, and the degree of resolution. In some embodiments, the sidewall 504 conforms to the cross-sectional shape of the base 502. More generally, however, the sidewall 504 need not conform to the shape of the base 502 and can have a variety of cross-sectional shapes different from the shape of the base 502. Further, the side wall 504 need not be cylindrical. In some embodiments, for example, the sidewall 504 may be curved along the axial direction of the Faraday cup 500.

  In general, the Faraday cup 500 may be relatively small. The maximum dimension of the Faraday cup 500 corresponds to the maximum linear distance between any two points on the cup. In some embodiments, for example, the maximum dimension of the Faraday cup 500 is 30 mm or less (eg, 20 mm or less, 10 mm or less, 5 mm or less, 3 mm or less).

  Typically, the thickness of the base 502 and / or the thickness of the sidewall 504 is selected to ensure efficient detection of charged particles. In some embodiments, the thickness of the base 502 and / or the thickness of the sidewall 504 is 5 mm or less (eg, 3 mm or less, 2 mm or less, 1 mm or less).

  The side wall 504 and base 502 of the Faraday cup 500 are generally made of one or more metals. Metals that can be used to make the Faraday cup 500 include, for example, copper, aluminum, and silver. In some embodiments, the Faraday cup 500 includes one or more coating layers on the surface of the base 502 and / or the sidewall 504. Such one or more coating layers can be made from materials such as copper, aluminum, silver, and gold.

  When charged particles are ejected from the ion trap 104 during operation of the analyzer 100, these charged particles can enter the Faraday cup 500 by drifting or accelerating. Once in the Faraday cup 500, charged particles are trapped on the surface of the Faraday cup 500 (the surface of the base 502 and / or the side wall 504). Charged particles trapped on either base 502 or sidewall 504 generate a current that is measured (eg, by an electrical circuit in detector 118) and reported to controller 108. If these charged particles are ions, the measured current is an ionic current and its amplitude is proportional to the measured current ion abundance.

  To obtain the mass spectrum of the analyte, the amplitude of the potential applied to the central electrode 302 of the ion trap 104 is changed (for example, a variable amplitude signal, a high voltage RF signal 482 is applied) Selectively discharges ions of mass to charge ratio. For each change in amplitude corresponding to a different mass to charge ratio, the ion current corresponding to the ejected ions of the selected mass to charge ratio is measured using the Faraday cup 500. The measured ionic current as a function of the potential applied to the electrode 302 corresponds to the mass spectrum and is reported to the controller 108. In some embodiments, the controller 108 converts the applied voltage to a specific mass to charge ratio based on the algorithm and / or the ion trap 104 calibration information.

  Following ejection from the ion trap 104 via the end cap electrode 306, charged particles can be accelerated to impact the detector 118 by forming an electric field between the detector 118 and the end cap electrode 306. In some embodiments, if the detector 118 includes, for example, the Faraday cup 500, the conductive surface of the Faraday cup 500 is maintained at the ground potential established by the power source 106, and a positive potential is applied to the end cap electrode 306. Is done. With these applied potentials, positive ions are repelled from the end cap electrode 306 toward the grounded conductive surface of the Faraday cup 500. Furthermore, since electrons passing through the end cap electrode 306 are attracted to the end cap electrode 306, they do not collide with the Faraday cup 500. This configuration therefore improves the signal to noise ratio. More generally, in this configuration, as long as the Faraday cup 500 is at a lower potential than the end cap electrode 306, it can be at any potential other than ground.

  In some embodiments, it is desirable to detect negatively charged particles (eg, negative ions and / or electrons). To detect such particles, the Faraday cup 500 is biased to a higher voltage than the end cap electrode 306 to attract negatively charged particles to the Faraday cup 500.

  In some embodiments, the detector 118 can include a Faraday cup 500 in which the two regions are separated by an insulating region. Different bias potentials can be applied to each region. For example, FIG. 5C shows a Faraday cup 500 that includes two conductive regions 510 and 520 separated by an insulating region 530. By grounding the end cap electrode 306 and applying positive and negative bias voltages to the regions 510 and 520, respectively, the region 510 can detect negative charged particles and the region 520 can detect positive charged particles. This configuration can simultaneously detect positively charged ions and negatively charged ions, thus providing additional information when measuring a mass spectrum. Alternatively, positively charged and negatively charged ions can be measured by first activating one of regions 510 and 520 by applying a bias potential and then activating the other region. Can be done in order. Alternatively, in some embodiments, the detector 118 can include two Faraday cups 500, where different bias voltages are used for the measurement of positively charged ions and negatively charged ions. Applied to each Faraday cup 500.

  In some embodiments, the detector 118 may be secured directly to the housing 122. For example, FIG. 5C shows that the housing 122 includes one or more electrodes 550 and 552 in contact with the Faraday cup 500. Alternatively, in some embodiments, one or more electrodes 550 and 552 may be attached directly to Faraday cup 500. In some embodiments, one electrode can be used to bias the Faraday cup 500 and another electrode can be used to measure the current generated by the Faraday cup 500. Alternatively, in some embodiments, this bias voltage application and current measurement can be performed using the same electrode.

  In some embodiments, the housing 122 can be configured such that the detector 118 can be easily attached and detached. For example, as shown in FIG. 5C, the housing 122 includes an opening through which the Faraday cup 500 can be secured and held by a holding element 540 (eg, a screw or other fastener). This is particularly advantageous when the Faraday cup 500 is broken or contaminated, which can be determined by detecting phantom peaks during mass spectrum measurement as described above. The contaminated Faraday cup 500 can be replaced by removing the cup 500 from the opening in the housing 122 and installing a replacement. Contaminated Faraday cups can be repaired or cleaned on the spot. For example, the Faraday cup 500 can be baked in a portable furnace so that sticky particles on the surface of the Faraday cup 500 are vaporized. The cleaned Faraday cup may be reinserted into the housing 122. This replacement allows the analyzer interruption time to be minimized even if some components of the analyzer 100 are contaminated. In some embodiments, the contaminated Faraday cup 500 can be cleaned by heating while attached to the housing 122 (eg, by applying a large current to the base 502 and the sidewall 504). Contaminant particles released from the surface of base 502 and / or sidewall 504 can be removed from the analyzer by pressure regulation subsystem 120.

  In some embodiments, as described in Section I, Faraday cup 500 is implemented as a component of pluggable and replaceable module 148. In this modular configuration, the Faraday cup 500 can be formed, for example, as a recess provided in the conductive material plate. This plate is directly attached to another component of the module 148, such as the ion trap 104, the opening of the end cap electrode 306 is aligned with this recess, and ions ejected from the ion trap 104 enter the Faraday cup directly. You may do it. Different types of analytes can be selectively detected using modules with different Faraday cup dimensions.

  FIG. 5D shows a detector 118 that includes an array of Faraday cup detectors 500, which may or may not be integrally formed. An array of detectors can be advantageous, for example, when the ion trap 104 includes an array of ion chambers 330. The end cap electrode 306 can include a plurality of apertures 560 aligned with each ion chamber, with ions ejected from each chamber passing substantially through only one of the apertures 560. After passing through one of the apertures 560, the ions are incident on any of the Faraday cup detectors 500 of the array. This array-based approach for ion ejection and detection significantly improves the efficiency with which the ejected ions are detected. In the array geometry shown in FIG. 5D, the size of each Faraday cup 500 can be matched to the size of each aperture 560 formed in the end cap electrode 306.

  In some embodiments, a biased repulsive grid or magnetic field can be placed in front of the Faraday cup 500 to prevent secondary charged particle emissions that can distort measurements of ejected ions from the ion trap 104. Alternatively, in some embodiments, secondary electron emission from the Faraday cup 500 can be used for detection of ejected ions.

  Although the discussion so far has focused on Faraday cup detectors with low power operation and compact size, more generally various other detectors can be used in the analyzer 100. For example, other suitable detectors include electron multipliers, photomultiplier tubes, scintillation detectors, image current detectors, daily detectors, phosphor-based detectors, and incident Included are other detectors where charged particles generate photons and are detected (ie, detectors that utilize a charge-photon energy conversion mechanism).

VI. Pressure Adjustment Subsystem The pressure adjustment subsystem 120 is generally configured to adjust the gas pressure in the gas path 128 including the internal volume of the ion source 102, ion trap 104, and detector 118. As described above in Section I, during operation of the analyzer 100, the pressure regulation subsystem 120 sets the gas pressure in the analyzer 100 to 100 millitorr or greater (e.g., 200 millitorr or greater, 500 millitorr or greater, 700 millitorr or greater, 1 Torr or more, 2 torr or more, 5 torr or more, 10 torr or more) and / or 100 torr or less (for example, 80 torr, 60 torr, 50 torr, 40 torr, 30 torr, 20 torr) .

  In some embodiments, the pressure regulation subsystem 120 maintains the gas pressure in some components of the analyzer 100 in the above range. For example, the pressure regulation subsystem 120 may adjust the gas pressure of the ion source 102 and / or the ion trap 104 and / or the detector 118 to between 100 millitorr and 100 torr (e.g., between 100 millitorr and 10 torr, 200 millitorr). 10 torr, between 500 mTorr and 10 Torr, between 500 mTorr and 50 Torr, between 500 mTorr and 100 Torr). In some embodiments, the gas pressures of at least two of the ion source 102, ion trap 104, and detector 118 are the same. In some embodiments, the gas pressure of all three components is the same.

  In some embodiments, the gas pressures of at least two of the ion source 102, ion trap 104, and detector 118 differ by relatively small amounts. For example, the pressure adjustment subsystem 120 may set the difference between at least two gas pressures of the ion source 102, the ion trap 104, and the detector 118 to 100 millitorr or less (e.g., 50 millitorr or less, 40 millitorr or less, 30 millitorr or less, 20 mTorr or less, 10 mTorr or less, 5 mTorr or less, 1 mTorr or less). In some embodiments, the difference in all gas pressures of the ion source 102, the ion trap 104, and the detector 118 is 100 mTorr or less (e.g., 50 mTorr, 40 mTorr, 30 mTorr, 20 mTorr, 10 mTorr or less, 5 mTorr or less, 1 mTorr or less).

  As shown in FIG. 6A, the pressure regulation subsystem 120 can include a scroll pump 600 with a pump vessel 606 that includes one or more interleaved scroll flanges 602 and 604. The relative orbital movement between the scroll flanges 602 and 604 traps gas and liquid and leads to a pumping action. In some embodiments, the scroll flange 604 can be fixed while the scroll flange 602 rotates around an eccentric track with or without rotation. In some embodiments, both scroll flanges 602 and 604 move with an eccentric center of rotation. FIG. 6B shows a schematic view of the scroll flange 602. Examples of scroll flange geometries include (but are not limited to) stretched lines, Archimedean spirals, and hybrid curves.

  Due to the orbital motion of the crawl flanges 602 and 604, the scroll pump 600 generates only very small amplitude vibrations and low noise during operation. Accordingly, the scroll pump 600 can be directly connected to the ion trap 104 without causing a substantially undesirable effect during mass spectrum measurement. To further reduce the oscillatory coupling, the orbiting scroll flange 602 can be balanced with a simple mass. Since the scroll pump 600 has few moving parts and generates only very small amplitude vibrations, the reliability of such a pump is generally very high.

  The scroll pump 600 is typically compact and has a small mass. In some embodiments, for example, the maximum dimension of the scroll pump 600 (e.g., the maximum linear distance between any two points on the scroll pump 600) is less than 10 cm (e.g., less than 8 cm, less than 6 cm, 5 cm Less than 4 cm, less than 3 cm, less than 2 cm). In some embodiments, the scroll pump 600 weighs less than 1.0 kg (e.g., less than 0.8 kg, less than 0.7 kg, less than 0.6 kg, less than 0.5 kg, less than 0.4 kg, less than 0.3 kg, less than 0.2 kg). is there.

  Since the scroll pump 600 is small in size and light in weight, the scroll pump can be incorporated into the analyzer 100 in various configurations. In some embodiments, for example, as shown in FIGS. 1D and 1E, the scroll pump 600 (as part of the pressure regulation subsystem 120) can be directly attached to the support base 140 (eg, a printed circuit board). is there. In some embodiments, the scroll pump 600 (as part of the pressure regulation subsystem 120) can be implemented as a component of a pluggable and replaceable module 148, and further includes an ion source 102, an ion trap 104, and / or Or it can be attached directly to one or more other components of the module 148, such as the detector 118.

  FIG. 6A shows the scroll pump 600 attached directly to the printed circuit board 608. FIG. The pump inlet 610 is directly connected to the pump inlet 620 of the manifold 121. The scroll pump 600 can be directly fixed to the substrate 608 by the fixing element 630 and the fixing element 632, which can be positioned at a position of 1 cm or more (for example, 2 cm or more, 3 cm or more, 4 cm or more) from the pump inlets 610 and 620, Accordingly, the oscillatory coupling between the pump 600 and the substrate 608 is reduced. Alternatively, rather than a direct connection between the pump 600 and the substrate 608, in some embodiments the pump inlet 610 and the pump inlet 620 may be connected by a tube (a flexible or rigid tube). .

  A scroll pump suitable for use in the pressure regulation subsystem 120 is commercially available from, for example, Agilent Technologies (Santa Clara, Calif.). In addition to the scroll pump, other pumps may be used in the pressure regulation subsystem 120. Examples of suitable pumps include membrane pumps, membrane pumps, and roots blower pumps.

  The use of a small, single mechanical pump provides several advantages over the pumping mechanism employed in conventional mass spectrometers. In particular, conventional mass spectrometers typically use multiple pumps, at least one of which operates at a high speed. Large mechanical pumps operating at high rotational speeds generate mechanical vibrations that can be coupled to other components of the analyzer, causing unwanted noise in the measurement information. Furthermore, even if steps are taken to isolate the component from such vibrations, the isolation mechanism typically increases the size of the analyzer, which can sometimes be greatly increased. Furthermore, large pumps operating at high speeds consume a large amount of power. Thus, conventional mass spectrometry includes large power supplies to meet these requirements, and further increases the size of such instruments.

  In contrast, a single mechanical pump, such as a scroll pump, can be used with the analyzers disclosed herein to control the gas pressure within each component of the system. By operating the mechanical pump at a relatively low rotational speed, the mechanical coupling of vibration to the other components of the analyzer is greatly reduced or eliminated. Furthermore, by operating at a low speed, the amount of power consumed by the pump is also small enough that the low requirements can be satisfied by the voltage source 106.

  In some embodiments, this single mechanical pump operates at a rate of less than 6000 cycles per minute (e.g., less than 5000 cycles per minute, less than 4000 cycles per minute, less than 3000 cycles per minute, less than 2000 cycles per minute). This allows the pump to maintain the desired gas pressure inside the analyzer 100 while at the same time its power consumption requirements can be met by the voltage source 106.

VII. Housing As described above in Section I, the mass spectrometer 100 includes a housing 122 that encloses the components of the analyzer. FIG. 7A shows a schematic diagram of an embodiment of the housing 122. The sample inlet 124 is integrated into the housing 122 and is configured to introduce gas particles into the gas path 128. A display device 116 and a user interface 112 are also integrated into the housing 122.

  In some embodiments, the display device 116 is an active or passive liquid crystal or light emitting diode (LED) display device. In some embodiments, the display device 116 is a touch screen display device. A controller 108 is connected to the display device 116, and various information can be displayed to the user of the mass spectrometer 100 using the display device 116. The displayed information can include, for example, information regarding the identity of one or more substances scanned by the analyzer 100. This information can also include mass spectrometry (eg, a measure of the abundance of ions detected by detector 118 as a function of mass to charge ratio). In addition, the information displayed includes operating parameters and information about the mass spectrometer 100 (e.g., measured ion current, voltages applied to various components of the mass spectrometer 100, current modules attached to the analyzer 100). 148, a name and / or identifier associated with 148, a warning associated with a substance identified by analyzer 100, and a set user preference for the operation of analyzer 100). Information such as user basic settings and operation settings that have been set can be stored in the storage device 114 and retrieved by the controller 108 for display.

  In some embodiments, as shown in FIG. 7A, the user interface 112 includes a series of control means incorporated into the housing 122. These control means are operable by the user of the analyzer 100 and may include buttons, sliders, rockers, switches, and other similar control means. By operating the control means of the user interface 112, the user of the analyzer 100 can activate various functions. For example, in some embodiments, activation of any of these control means initiates a scan by the analyzer 100, during which time the analyzer draws a sample (eg, gas particles) into the sample inlet 124 and the gases Ions are generated from the particles and further captured and analyzed using the ion trap 104 and detector 118. In some embodiments, if any control means is activated, the analyzer 100 is reset before performing a new operation. In some embodiments, the analyzer 100 may be activated by a user (eg, after replacing any of the components of the analyzer 100 such as a filter connected to the module 148 and / or the sample inlet 124). ) Includes control means for restarting the analyzer 100.

  If the display device 116 is a touch screen display device, some or even part of the user interface 112 can be implemented as a series of touch screen control means on the display device 116. That is, part or all of the control means of the user interface 112 can be a touch-sensitive area of the display device 116 that can be operated by the user by touching the display device 116 with a finger.

  As described above in Section I, in some embodiments, the mass spectrometer 100 includes a replaceable pluggable module 148 that includes an ion source 102, an ion trap 104, and (optionally) a detector 118. be able to. If the mass spectrometer 100 includes a pluggable module 148, the housing 122 can include an opening that allows a user to access the interior of the housing 122 and replace the module 148 without disassembling the housing 122. FIG. 7B is a cross-sectional view of mass spectrometer 100 including pluggable module 148. FIG. In FIG. 7B, the housing 122 includes an opening 702 and a partition 704 that closes the opening 702. When replacing module 148, the user of analyzer 100 can open partition 704 to expose the interior of analyzer 100. The partition 704 is arranged to allow direct access to the pluggable module 148 so that the user can remove the module 148 from the support base 140 and install another module instead without disassembling the housing 122. . Then, the user can close the opening 702 again by fixing the partition 704.

  In FIG. 7B, the divider 704 is realized in the form of a retractable door. More generally, however, various partitions may be used to close the opening of the housing 122. For example, in some embodiments, the divider 704 may be implemented as a lid that is completely removable from the housing 122.

  In general, the mass spectrometer 100 can include a variety of different sample inlets 124. For example, in some embodiments, the sample inlet 124 includes an aperture configured to draw gas particles directly from the ambient environment of the analyzer 100 into the gas path 128. The sample inlet 124 can include one or more filters 706. For example, in some embodiments, the filter 706 is a HEPA filter and prevents dust and other solid particles from entering the analyzer 100. In some embodiments, the filter 706 includes a molecular sieve material that traps water molecules.

  As mentioned above, conventional mass spectrometry operates at a low internal gas pressure. In order to maintain a low gas pressure, conventional mass spectrometers include one or more filters attached to the sample inlet. These filters are optional and filter certain types of substances such as atmospheric gas particles (eg, nitrogen and / or oxygen molecules) from entering the mass spectrometer. These filters may be particularly adapted for certain types of analytes such as biological molecules, and other types of molecules can be filtered out. As a result, the filters used in conventional mass spectrometers can include pinch valves and thin film filters made of materials such as polydimethylsiloxane that allow for selective movement of substances, allowing the flow of incoming gas particles. The stream is filtered to remove certain types of particles from the stream. Without such a filter, a conventional mass spectrometer will not work, but it will not be able to maintain a low gas pressure, and some of the particles introduced into this mass spectrometer should interfere with the operation of some components. That's why. As an example, the thermionic source used in conventional mass spectrometers does not operate in the presence of somewhat concentrated air oxygen.

  There are several drawbacks to using specific material filters in conventional mass spectrometers. For example, since these filters are selective, only a few types of specimens can be analyzed without changing filters and / or operating conditions that can be a cumbersome task. In particular, it may be difficult for a user who is not proficient in a mass spectrometer to reconfigure the analyzer for a particular sample by choosing an appropriate selective filter. Furthermore, the filters used in conventional mass spectrometers cause a time delay because analyte particles do not diffuse instantaneously through the filter. Depending on the selectivity of the filter and the concentration of the analyte, there will be a considerable delay between the time when the analyte first contacts and the time when a sufficient amount of analyte ions is detected to generate mass spectral information. There is.

  However, because the mass spectrometer disclosed herein operates at higher pressures, it is not necessary to maintain a low gas pressure within the analyzer, including filters such as thin film filters. By operating without the types of filters used in conventional mass spectrometers, the analyzers disclosed herein can analyze a greater number of different types of samples without significant reconstitution and are faster to analyze Can be executed. In addition, the analyzer components disclosed herein are generally less sensitive to atmospheric gases such as nitrogen and oxygen, which can be introduced into the analyzer along with the analyte particles of interest, which increases the speed of the analysis. Improve and reduce operating requirements of other components of the analyzer (eg, pumping load of pressure regulation subsystem 120).

  Thus, in general, the filters (eg, filter 706) used in the analyzers disclosed herein do not filter atmospheric gas particles (eg, nitrogen and oxygen molecules) from the gas particle stream entering the sample inlet 124. . In particular, the filter 706 passes at least 95% or more of atmospheric gas particles in contact with the filter.

  Different types of filters 706 can be exchanged and can be exchanged by the user of the analyzer 100 if they become dirty or less effective. In some embodiments, the mass spectrometer 100 can include multiple filters 706, and the user can selectively attach any one or more of these filters, depending on the nature of the sample being analyzed. it can.

  In some embodiments, the sample inlet 124 can be configured to receive the substance to be analyzed by direct injection. For example, the filter 706 may be replaced with a sample injection port attached to the sample inlet 124. When the analyzer 100 is used, a substance injected into the sample introduction port 124 through this sample injection port is introduced into the gas path 128, ionized by the ion source 102, and analyzed by the ion trap 104 and the detector 118. .

  In some embodiments, the analyzer 100 can include various sample introduction modules that can be attached to the housing 122 to introduce different types of analytes into the analyzer 100. A sample introduction module 750 is schematically illustrated in FIG. 7C. Module 750 is attached to housing 122 such that electrode 752 in housing 122 establishes an electrical connection with a corresponding electrode in module 750. The electrode 752 is connected to the controller 108 and the voltage source 106 on the support base 140. The voltage source 106 can supply power to the module 750 via the electrode 752, and the controller 108 and the module 750 send and receive signals. When the module 750 is attached to the housing 122 (eg, using either a thread or key lock connection, a magnetic attachment mechanism, or various other attachment mechanisms), the voltage source 106 automatically supplies power. To activate module 750. Once activated, the module 750 reports its identity to the controller 108, and the controller can display information on the activated module on the display device 116. The controller 108 can receive configuration settings and other operating parameters from the storage device 114, so the analyzer 100 is automatically configured to analyze the sample introduced via the module 750.

  In general, various sample introduction modules can be used with the analyzer 100. For example, in some embodiments, module 750 is a steam thermal desorption module. In some embodiments, module 750 is a low temperature plasma module. In some embodiments, module 750 is an electrospray ionization module. Each of these modules can be used interchangeably in the analyzer 100 and can analyze a wide variety of different samples.

  In addition to the replaceable module 750, the analyzer 100 can include various sensors. For example, in some embodiments, the mass spectrometer 100 can include a limit sensor 708 coupled to the controller 108. The limit sensor 708 detects gas particles in the environment surrounding the mass spectrometer and reports the gas concentration to the controller 108. During operation of the mass spectrometer 100 by the user, the controller 108 monitors the duration and concentration of the gas measured by the limit sensor 708 and alerts if the user's exposure to gas particles exceeds a threshold concentration or threshold time limit. Are displayed to the user (eg, via display device 116). Information regarding the threshold exposure concentration and the time limit can be stored in the storage device 114 and retrieved by the controller 108, for example. Exemplary limit sensors that can be used with mass spectrometer 100 include flammable / low explosion level gas sensors, photoionization sensors, electrochemical sensors, and temperature and humidity sensors.

  In some embodiments, the mass spectrometer 100 can include an explosion hazard sensor 710. An explosion danger sensor 710 is connected to the controller 108 and detects the presence of an explosion generating substance in the vicinity of the analyzer 100. The threshold concentrations of various explosive substances are stored in the storage device 114 and can be retrieved by the controller. When the analyzer 100 is in operation, the controller 108 can display a warning message to the user of the analyzer 100 via the display device 116 if the concentration of the one or more explosives measured by the sensor 710 exceeds a threshold value. . In some embodiments, this warning message may be sent to the user to stop using the analyzer 100 or to prevent it from firing in the auxiliary shield (eg, cage) to prevent ignition of the one or more explosives. Can advise to use. Explosion hazard sensors that can be used with mass spectrometer 100 include, for example, combustible sensors available from MSA (Canterbury Township, Pa.) And RAE Systems (San Jose, Calif.).

The housing 122 is generally shaped so that the user can comfortably operate with one or both hands. In general, the housing 122 can have a wide variety of different shapes. However, the selection and integration of the components of the analyzer 100 disclosed herein makes the housing generally compact. As shown in FIGS. 7A and 7B, regardless of the overall shape, the housing 122 has a maximum dimension a ₁ corresponding to the longest linear distance between any two points on the outer surface of the housing. In some embodiments, a ₁ is 35 cm or less (e.g., 30 cm or less, 25 cm or less, 20 cm or less, 15 cm or less, 10 cm or less, 8 cm or less, 6 cm or less, 4 cm or less) is .

  In addition, the selection of components within the analyzer 100 makes the overall weight of the analyzer 100 significantly lower than conventional mass spectrometers. In some embodiments, the overall weight of the analyzer 100 is 4.5 kg or less (eg, 4.0 kg or less, 3.0 kg or less, 2.0 kg or less, 1.5 kg or less, 1.0 kg or less, 0.5 kg or less).

VIII. Modes of Operation In general, mass spectrometer 100 operates according to a variety of different modes of operation. FIG. 8A shows a general sequence of steps performed in different modes of operation for scanning and analyzing a sample. In the first step 802, scanning of the sample is started. In some embodiments, this scan is initiated by a user of analyzer 100. For example, the analyzer 100 can be configured to operate in a “one touch” mode in which a user can initiate a scan of a sample simply by activating the control means of the user interface 112. FIG. 8B shows one embodiment of the analyzer 100 that includes a control means 820 for the user interface 112 to initiate a scan. When the control means 820 is activated by the user, scanning of the sample (shown as gas particles 822 in FIG. 8B) is started.

  In some embodiments, the controller 108 can automatically initiate a scan based on one or more sensor readings. For example, if the analyzer 100 includes limit sensors such as photoionization detectors and / or LEL sensors, the controller 108 can monitor signals from these sensors. For example, if these sensors indicate that a target substance has been detected, the controller 108 can begin scanning. In general, the controller 108 can use a wide variety of different sensor-based events or conditions to initiate scanning automatically.

  In some embodiments, the analyzer 100 can be configured to run in a “continuous scan” mode. When the analyzer 100 is placed in the continuous scanning mode, scanning is repeatedly started at every fixed interval. The time interval can be configured by the user, and the value of the time interval can be stored in the storage device 114 and retrieved by the controller 108. Thus, in step 802 of FIG. 8A, when the analyzer 100 is in the continuous scan mode, scanning is initiated by the analyzer.

  After this scan is started, the sample is introduced into the analyzer 100 at step 804. A variety of different methods can be used to introduce the sample into the analyzer. In some embodiments, if the sample consists of gas particles (e.g., gas particles 822 in FIG.8B), the controller 108 activates the valve 129 to open the valve and place the gas particles in the analyzer 100 (e.g., Into the gas path 128). If the sample inlet 124 includes a filter 706, the gas particles pass through the filter, which removes dust and other solid materials from the gas particle stream. As described above, the pressure regulation subsystem maintains a gas pressure below atmospheric pressure in the gas path 128. As a result, when the valve 129 is opened, the gas particles 822 are drawn into the sample inlet 124 due to the differential pressure between the gas path 128 and the environment surrounding the analyzer 100. Alternatively or additionally, pressure regulation subsystem 120 may cause gas particles to flow into analyzer 100.

  In some embodiments, the sample can be introduced into the analyzer 100 by direct injection. As described above in Section VII, the analyzer 100 can include a sample injection port connected to the sample inlet 124. This sample injection port allows the user of the analyzer 100 to inject the sample directly into the sample inlet 124 for analysis. Once injected, the sample enters gas path 128.

  In some embodiments, a partially ionized sample can be drawn into the analyzer 100 by electrostatic or current forces. For example, charged particles can be accelerated into the analyzer 100 (eg, via the sample inlet 124) by applying an appropriate potential to the electrodes of the analyzer 100.

  Subsequently, in step 806, the sample is ionized in the ion source 102. As described above, the sample inlet 124 can be located at different locations along the gas path 128 relative to the other components of the analyzer 100. For example, in some embodiments, the sample inlet 124 can be positioned such that gas particles introduced into the analyzer 100 first enter the ion trap 104 from the sample inlet 124. For example, in some embodiments, the sample inlet 124 can be positioned such that gas particles introduced into the analyzer 100 first enter the ion source 102 from the sample inlet 124. In some embodiments, the sample inlet 124 can be positioned such that gas particles first enter the detector 118 from the sample inlet 124. Further, the sample inlet 124 can be arranged such that gas particles entering the analyzer 100 enter the gas path 128 from a point between the ion source 102 and / or the ion trap 104 and / or the detector 118.

  After a sample (eg, as gas particles 822) is introduced into the analyzer 100 at a point along the gas path 128, some of the gas particles enter the ion source. If the sample inlet 124 is not arranged so that the gas particles 822 enter the ion source 102 directly, the movement of the gas particles 822 into the ion source 102 occurs by diffusion. Upon entering the ion source 102, the controller 108 activates the ion source 102 to ionize the gas particles as disclosed in Section II.

  Next, the ions generated in step 806 are trapped in the ion trap 104 in step 808. As described above in Section II, the movement of ions from the ion source 102 to the ion trap 104 generally occurs under the influence of an electric field generated between the ion source 102 and the ion trap 104. Once inside the ion trap 104, ions are trapped by the electric field inside the trap and circulate within the opening of the central electrode 302 and between the end cap electrodes 304 and 306. The electric field in the ion trap 104 is generated by the voltage source 106 under the control of the controller 108, which applies an appropriate potential to the electrodes 302, 304, and 306 to generate a trapping electric field.

  In step 810, trapped and circulating ions in the ion trap 104 are selectively ejected from the trap. As described above in Section III, selective ejection of ions from the trap 104 is performed under the control of the controller 108, which provides a signal for changing the amplitude of the RF voltage applied to the central electrode 302. Transmit to the voltage source 106. When the amplitude of this potential changes, the amplitude of the electric field in the inner opening of the center electrode 302 also changes. In addition, when the amplitude of the electric field in the central electrode 302 changes, circulating ions with a specific mass-to-charge ratio fall from the trajectory in the central electrode 302 and are ion trapped through one or more apertures in the end cap electrode 306. Discharged from 104. The controller 108 sweeps the amplitude of the applied potential according to a defined function (eg, a linear amplitude sweep) to selectively eject ions of a specific mass to charge ratio from the ion trap 104 into the detector 118. Configured. The rate at which the applied voltage is swept can be determined automatically by the controller 108 (eg, to achieve the target resolution of the analyzer 100) and / or can be set by the user of the analyzer 100.

  As these ions are selectively ejected from the ion trap 104, they are detected by the detector 118 in step 812. As disclosed in Section V, these ions can be detected using a wide variety of different detectors. For example, in some embodiments, the detector 118 includes a Faraday cup that is used to detect these ejected ions.

  For each mass to charge ratio selected by the amplitude of the charge applied to the central electrode 302 within the ion trap 104, the detector 118 measures the current associated with the abundance of ions detected at the selected mass to charge ratio. To do. The measured current is sent to the controller 108. As a result, the information that the controller 108 receives from the detector 118 corresponds to the abundance of ions detected as a function of the mass to charge ratio of these ions. This information corresponds to the mass spectrum of the sample.

  More generally, the controller 108 is configured to detect ions according to the mass-to-charge ratio of ions, which causes the controller 108 to detect or receive signals that correlate to and are related to the detection of ions. It means to do. In some embodiments, the controller 108 detects or receives information about ions as a direct function of mass to charge ratio. In some embodiments, the controller 108 receives information about the ions as a function of another amount related to the mass-to-charge ratio of the ions, such as the potential applied to the ion trap 104, for example. In all these embodiments, the controller 108 detects ions according to the mass to charge ratio.

  In step 814, the information received from detector 118 is analyzed by controller 108. In general, to analyze this information, the controller 108 (eg, the electronic processor 110 in the controller 108) compares the sample's mass spectrum with reference information to determine whether the sample's mass spectrum indicates any known material. Judging. This reference information is stored in, for example, the storage device 114 and can be retrieved by the controller 108 for analysis. In some embodiments, the controller 108 may retrieve reference information from a database stored at a remote location. For example, for use in analyzing information measured by detector 118, controller 108 can communicate with such a database using communication interface 117 to obtain a mass spectrum of a known substance.

  Information measured by the detector 118 is analyzed by the controller 108 to determine information regarding sample identity. When the sample includes a large number of compounds, the controller 108 can obtain information related to the identification of some or all of the large number of substances by comparing measurement information from the detector 118 with reference information.

  The controller 108 is configured to determine various information regarding the identity of one sample. For example, in some embodiments, this information includes one or more of the sample's common name, IUPAC name, CAS number, UN number, and / or its chemical formula. In some embodiments, information about the identity of a sample can be obtained from whether the sample belongs to a particular type of material (eg, explosives, high energy materials, fuels, oxidants, strong acids or bases, poisons). Contains information. In some embodiments, this information can include information regarding hazards associated with the sample, handling instructions, safety warnings, and reporting instructions. In some embodiments, this information can include information regarding the concentration or level of the sample as measured by the analyzer.

  In some embodiments, this information can include an indication of whether the sample matches the target material. For example, once the scan is initiated at step 802, the user of the analyzer 100 can place the analyzer in a target mode, in which case the analyzer 100 scans the sample, and in particular a series of identified samples. Judge whether it matches any of the target substances. The controller 108 can look for specific spectral features in the measured mass spectral information using various data analysis techniques such as digital filtering and expert systems. For a particular target material, the controller 108 can look for mass spectral features that are characteristic of that target material, such as a peak at a particular mass to charge ratio. If a particular spectral feature is missing from the measured mass spectral information, or if the measured information contains a spectral feature that should not appear, the information about the identity of the sample identified by the controller 108 will indicate that the sample is the target substance May include an indication that it does not match. The controller 108 can be configured to identify such information for a number of target substances.

  After the sample analysis is complete, the controller 108 displays information about the sample to the user using the display device 116 at step 816. The displayed information varies depending on the operation mode of the analyzer 100 and the user's operation. As disclosed in Section I, the analyzer 100 is configured for use by a person who has not received special training in the interpretation of mass spectra. For those who have not undergone such training, a complete mass spectrum (eg, ion abundance as a function of mass-to-charge ratio) is often largely unknown. As a result, the analyzer 100 is configured not to display the measured mass spectrum of the sample to the user at step 816. Instead, the analyzer 100 displays only a part (or all) of the information regarding the identity of the sample determined in step 814 to the user. For users who have not received special training, information on sample identity is most meaningful.

  In addition to information regarding sample identity, the controller 108 can also display other information. For example, in some embodiments, the analyzer 100 can access a database of known dangerous substances (eg, stored in a storage device or accessible via the communication interface 117). If information regarding the identity of the sample is present in the dangerous substance database, the controller 108 can display a warning message and / or additional information to the user. This alert message may include, for example, information regarding the relative risk of the sample. This additional information may include actions to be taken by the user, including, for example, actions that limit the exposure of the user or others to the substance and other security related actions.

  In some embodiments, the analyzer 100 is configured to display the mass spectrum of the sample to the user when the control means is activated. Referring to FIG. 8B, the user interface 112 includes control means 824 that, when activated by the user, displays the mass spectrum of the sample on the display device 116. By means of the control means 824, a person trained in the interpretation of the mass spectrum can directly view the information measured by the detector 118. This information can be useful, for example, when a clear match between measured mass spectral information and reference information cannot be obtained. Furthermore, if the analyzer 100 is used for laboratory analysis, the user can activate the control means 824 to infer more detailed chemical information, such as fragmentation of specific ions, for example. In some embodiments, the analyzer 100 is configured to display the sample mass spectrum only when the control means 824 is activated by the user and / or only after information regarding the identity of the sample is displayed. The That is, by configuring the analyzer 100, detailed mass spectrum information is not displayed to the user during normal operation, and the user can view this detailed information only by the operation of the control means 824.

  In some embodiments, the control means 824 can be configured to allow two different modes of operation. For example, when the control means 824 is activated to the first state by the user of the analyzer 100, information regarding the identity of the sample is displayed to the user when the analysis is complete. When the control means 824 is activated to the second state, mass spectral information (eg, abundance of ions as a function of mass to charge ratio) is displayed. Therefore, the control means 824 can be in the form of a two-way switch that allows the user to select a desired information display mode during operation of the analyzer. In some embodiments, when the control means 824 is activated to the second state, the analyzer 100 can be configured to display information regarding the identity of the sample in addition to the mass spectral information.

  In step 816, the process shown in flowchart 800 ends. If this scan is initiated by the user actuating the control means 820 in step 802, the analyzer 100 waits for the control means 820 to be actuated to begin the next scan. Alternatively, if the analyzer 100 is in continuous scan mode, the analyzer 100 waits for a defined time interval and automatically starts the next scan after that time interval has elapsed, Wait for another external trigger, such as a sensor signal.

  As described above, the analyzer 100 generally does not use a filter that filters atmospheric gas particles. As a result, when analyte particles are introduced into the analyzer, atmospheric gas particles are also introduced, and a mixture of gas particles is formed within the analyzer 100. The analyzer 100 is disclosed herein because it operates at a pressure significantly higher than the internal pressure of a conventional mass spectrometer and because the components of the analyzer 100 are generally relatively insensitive to atmospheric gas particles. Using an analyzer, the sample can be introduced in a manner not possible with a conventional mass spectrometer. In particular, the introduction of the sample particles can be performed by continuously drawing the mixture of the particles without filtering the particles of the sample and the atmospheric gas particles. In some embodiments, the analyzer 100 passes the mixture of gas particles through the sample inlet 124 into the gas path 128 for at least 10 seconds (e.g., at least 15 seconds, at least 20 seconds, at least 30 seconds, at least 45 seconds). Second, at least 1 minute, at least 1.5 minutes, at least 2 minutes, at least 3 minutes, at least 4 minutes, at least 5 minutes) or more.

  As the analyte particles are introduced continuously over an extended period of time, the analyzer 100 adjusts the duty cycle of the ion source 102 so that the ion source 102 remains in the extended period of time (eg, a portion of the period during which the analyte particles are introduced). Or all) ions are generated. As described above, the duty cycle of the ion source 102 can generally be adjusted to control the period during which ions are generated (eg, by adjusting the period 274 in FIG. 2I). In some embodiments, the analyzer 100 adjusts the duty cycle so that ions are drawn by the ion source 102 for 10 seconds or more (e.g., 20 seconds or more, 30 seconds or more, 40 seconds or more, 50 seconds or more, 1 minute or more, 1.5 minutes or more). Min., 2 min., 3 min., 4 min., 5 min.).

  As described above, the analyzer 100 achieves both compactness and low power operation by removing the high power consumption components typically found in conventional mass spectrometers. Of these components, vacuum pumps, especially turbomolecular pumps, are heavy and consume large amounts of power. The analyzer 100 does not include such a pump, and as a result is significantly lighter and consumes much less power than a conventional mass spectrometer.

  By using the pressure regulation subsystem 120, the mass spectrometer 100 operates at an internal gas pressure that is significantly higher than the internal gas pressure of a conventional mass spectrometer. In general, at higher pressures, the resolution of a mass spectrometer is reduced by various mechanisms including collision-induced line broadening and ion-neutral charge exchange. Therefore, the internal gas pressure in the mass spectrometer should be kept as low as possible in order to obtain as high a resolution mass spectrum as possible.

  However, as mentioned above, useful information about the sample, including information about the identity of the sample, can be obtained by measuring the mass-to-charge ratio of the sample even if the resolution of the mass spectrometer is below the highest possible value. And can be given to the user. In particular, a sufficiently accurate match between measured mass spectral information and reference information is sufficient when the mass spectrometer 100 operates at a higher internal gas pressure than a conventional mass spectrometer and therefore at a lower resolution. Can also be achieved.

  Because the mass spectrometer 100 operates at a lower resolution than a conventional mass spectrometer, in some embodiments, the mass spectrometer 100 has several components to further reduce its overall power consumption. Can be further configured to adaptively adjust the operation of In order to achieve the target resolution in the measured mass spectral information or to achieve a sufficient match between the mass spectral information and the reference information for known substances or conditions, the components are operated adaptively .

  FIG. 8C shows a flowchart 850 that includes a series of steps of the adaptive operation of the mass spectrometer 100 to achieve sufficient agreement between the measured mass spectral information and the reference information for known substances or conditions. The target resolution can be set by the user of the mass spectrometer 100 (eg, by user-defined settings or by visual inspection of measured mass spectral information), or the controller 108 can set it automatically. In a first step 852, a scan is initiated in the same manner as described above in connection with step 802. Subsequently, at step 854, the sample is introduced into the analyzer 100 in the same manner as described above in connection with step 804. In step 856, the sample particles are ionized to generate ions, as described above in connection with step 806.

  Subsequently, in step 858, the sample ions ionized by the ion source 102 are detected using the detector 118. Step 858 can be performed without activating the ion trap 104 to capture or selectively eject ions. Instead, at step 858, ions generated by the ion source 102 pass directly through the end cap electrodes 304 and 306 of the ion trap 104 and enter the detector 118. The voltage source 106 can be configured to apply a potential to the electrodes of the ion source 102 and the detector 118, and an electric field can be formed between the ion source 102 and the detector 118 to facilitate the movement of ions.

  Next, in step 860, the controller 108 determines whether or not a threshold ion current has been detected by the detector 118. The threshold ion current may be a user-defined setting of the analyzer 100 and / or a user adjustable setting. Alternatively, the threshold ion current may be automatically determined by the analyzer 100 based on, for example, dark current and / or noise measurements at the detector 118 by the controller 108. If the threshold current has not been reached, sample ionization and sample ion detection continues at steps 856 and 858. Further, if the threshold current has been reached, the controller 108 activates the ion trap 104 at step 862 to trap and selectively eject ions into the detector 118. These ejected ions are measured by detector 118 and their mass spectral information is analyzed by controller 108 at step 864 to determine information regarding sample identity.

  As part of the analysis at step 864, the controller 108 can determine the probability that the measured mass spectral information of the sample results from a known substance or condition. In step 866, the controller 108 compares the determined probability with a threshold probability to determine whether the analysis of this mass spectral information is limited by the resolution of the analyzer 100. If this probability is greater than the threshold, the controller 108 displays information about the sample (eg, information about sample identity and / or sample identity) using the display device 116, and the process ends at step 870. To do.

  However, if this probability is lower than the threshold probability value at step 866, the analysis of this mass spectral information may be limited by the resolution of the analyzer 100. To improve the resolution of the analyzer 100, the controller 108 adaptively adjusts the analyzer configuration before processing returns to step 862.

  The controller 108 is configured to adjust its configuration in various ways to improve the resolution of the analyzer 100. In some embodiments, the controller 108 is configured to operate the buffer gas source 150 to introduce buffer gas into the gas path 128. The introduced buffer gas particles can include, for example, nitrogen molecules, hydrogen molecules, or atoms of a noble gas such as helium, argon, neon, or krypton. The buffer gas source 150 can include a replaceable cylinder containing buffer gas particles and a valve or buffer gas generator connected to the controller 108 via a control line 127a. The controller 108 can be configured to actuate a valve of the buffer gas source 150 such that a controlled amount of buffer gas particles is released into the gas path 128. Once released into the gas path 128, the buffer gas particles mix with the ions generated by the ion source 102, facilitating ion capture and selective ejection into the detector 118, and thus the analyzer 100. Improve the resolution.

  In some embodiments, the controller 108 reduces the internal gas pressure of the analyzer 100 to increase the resolution of the analyzer 100. In order to reduce the internal gas pressure, the controller 108 activates the pressure regulation subsystem 120 via the control line 127d. Alternatively or additionally, the controller 108 can close the valve 129 to reduce the internal gas pressure. In some embodiments, the valves 129 can be alternately opened and closed in a pulsed manner with a specific duty cycle to reduce the internal gas pressure. In some embodiments, the analyzer 100 can include multiple sample inlets, and the valve 129 can be closed to seal the sample inlet 124, while at the same time provided at a smaller diameter sample inlet. Another in-line valve can be opened. By reducing the gas pressure in the analyzer 100 using a different sample inlet, there is no need to change the pumping speed. Decreasing the internal gas pressure of the analyzer 100 increases the resolution of the analyzer 100 by reducing the frequency of collisions between ions in the ion source 102, ion trap 104, and detector 118.

  In some embodiments, to improve the resolution of the analyzer 100, the controller 108 increases the frequency with which the potential applied to the central electrode 302 changes. By reducing the rate at which the applied potential changes, the rate at which the internal electric field of the electrode 302 changes also decreases. As a result, the selectivity with which ions are discharged from the ion trap 104 is increased, and the resolution of the analyzer 100 is improved.

  In some embodiments, the controller 108 is configured to change the axial field frequency or amplitude in the ion trap 104 to change the resolution of the analyzer 100. Changes in the axial electric field in the ion trap 104 move the discharge boundary of the ion trap, thereby extending or reducing the high mass range of the analyzer and modifying the resolution and / or resolution of the analyzer 100.

  In some embodiments, the controller 108 is configured to increase the resolution of the analyzer 100 by changing the duty cycle of the ion source 102. It has been experimentally observed that the reduction in ionization time improves the resolution of the mass spectrometer 100. Thus, referring to the graph 270 of FIG. 2I, the resolution of the analyzer 100 can be reduced by reducing the period 274 during which the bias potential 272 is applied to the ion source 102 (eg, reducing the duty cycle of the ion source 102). Can be improved.

  Conversely, reducing the resolution of the analyzer 100 can also be useful in certain situations. For example, referring to graphs 270 and 280 in FIG. 2I, by increasing the time period 274 during which the bias potential 272 is applied to the ion source 102 (eg, increasing the duty cycle of the ion source 102), thus the ion trap 104's. By reducing the period during which the amplitude of the potential applied to electrode 302 is increased (periods 284 and 286 of graph 280), the resolution of analyzer 100 is reduced, but the sensitivity of analyzer 100 is improved, and thus The signal to noise ratio of the mass spectral information measured using the analyzer 100 increases. This increased sensitivity can be particularly useful when trying to detect certain substances at very low concentrations.

  In some embodiments, the controller 108 increases the resolution of the analyzer 100 by increasing the time period during which the potential applied to the electrode 302 of the ion trap 104 is increased (eg, the interval 286 in FIG. 2I). It is configured. By increasing the sweep period, the circulating ions are ejected at a lower speed from the ion trap 104, thereby increasing the resolution of the measured mass spectral information.

  In some embodiments, the controller 108 is configured to change the resolution of the analyzer 100 by adjusting the ramp profile associated with the amplitude sweep of the potential applied to the electrode 302. As shown in graph 280 of FIG. 2I, the amplitude of the potential applied to electrode 302 typically increases according to a linear ramp function. More generally, however, the controller 108 can be configured to increase the amplitude of the potential applied to the electrode 302 according to different ramp functions. For example, the ramp profile can be adjusted by the controller 108 such that the applied potential increases according to a series of different linear ramp profiles, each representing a different rate of the potential increase. In another example, the ramp profile can be adjusted such that the amplitude of the potential applied to electrode 302 increases according to a non-linear function such as an exponential function or a polynomial function.

  As described above, the controller 108 is configured to perform one or more of the operations described above to change the resolution of the analyzer 100. The order in which these operations are performed may be determined by the analyzer 100 or may be determined by user basic settings. For example, in some embodiments, a user of the analyzer 100 can perform any of the above steps in any order to increase the resolution of the analyzer 100 and / or reduce power consumption. You can specify whether to execute. Such user selections can be stored in the storage device 114 as a set of basic settings. Alternatively, in some embodiments, the order of operations performed by the controller 108 may be permanently encoded in the logic circuitry of the controller 108 or stored as a non-modifiable setting in the storage device 114. Also good.

  In some embodiments, the controller 108 can determine the order of operations based on other considerations. For example, to ensure that the power consumption of the analyzer 100 is minimized, the order of operations performed by the controller 108 to improve the resolution of the analyzer 100 can be determined according to the increase in power consumption as a result of each operation. The controller 108 can be configured with information on how each of the operations described above increases overall power consumption, and can select an appropriate sequence of operations based on this power consumption information, thereby increasing power consumption. The operation that minimizes is performed first. Alternatively, the controller 108 can be configured to measure an increase in power consumption associated with each operation and can further select the order of operations based on the measured power consumption value.

  In flowchart 850, adjustment of the configuration of analyzer 100 is based on the probability that the measured mass spectral information matches known reference information, whereas adjustment of the configuration of analyzer 100 is based on other criteria. Also good. In some embodiments, for example, adjusting the configuration of the analyzer 100 may be based on whether the target resolution of the analyzer 100 has been achieved. In step 864, the controller 108 determines the actual resolution of the analyzer 100 based on the measured mass spectral information (eg, based on the FWHM of a single ion peak within the measurement window of the analyzer 100). In step 866, the actual resolution is compared by the controller 108 to the target resolution of the analyzer 100. If the actual resolution is lower than the target resolution, the controller 108 adjusts the configuration of the analyzer in step 872 in order to improve the resolution of the analyzer 100 as described above.

Hardware, software, electronic processing Any method steps, features, and / or attributes disclosed herein may be based on the controller 108 (e.g., the electronic processor 110 of the controller 108) and / or standard programming techniques. It can be executed by one or more additional electronic processors (eg, computers or programmed integrated circuits) that execute the program. Such a program may be a programmable computing device or special device, each including a processor, a data storage system (including memory and / or storage elements), at least one input device, and at least one output device such as a display device or printer. Designed to run on integrated circuits designed for Program code is applied to input data to perform functions and generate output information that is applied to one or more output devices. Each such computer program is preferably implemented in a high level procedural or object oriented programming language or assembly or machine language. Furthermore, such languages may be compiled or translated languages. Each such computer program can be stored on a computer-readable storage medium (eg, a CD-ROM or magnetic disk) that, when read by the computer, causes the processor of the computer to perform the analysis and control functions described herein. .

Other Embodiments In some embodiments, the analyzer 100 is configured to operate at high gas pressures, for example, up to 1 atmosphere (eg, 760 Torr). That is, one or more internal gas pressures of the ion source 102, the ion trap 104, and / or the detector 118 are 100 Torr and 760 Torr when the analyzer 100 detects ions according to the mass to charge ratio of the ions. (For example, 200 Torr or more, 300 Torr or more, 400 Torr or more, 500 Torr or more, 600 Torr or more).

  Some components disclosed herein are already suitable for operation at pressures up to 1 atmosphere (and higher). For example, some of the ion sources disclosed herein, such as glow discharge ion sources, can operate at pressures up to 1 atmosphere with little or no modification. In addition, certain detectors, such as Faraday detectors (eg, Faraday cup detectors and arrays thereof) can operate at pressures up to 1 atmosphere with little or no modification.

The ion trap disclosed herein can be modified to operate at pressures up to 1 atmosphere. For example, referring to FIG. 3A, to operate at a pressure of 1 atmosphere, the dimension c ₀ of the ion trap 104 is between 1.5 and 0.5 microns (eg, between 1.5 and 0.7 microns, 1.2 microns). Should be reduced to between 0.5 microns, between 1.2 microns and 0.8 microns, approximately 1 micron). Furthermore, to operate at a gas pressure of up to 1 atm, the voltage source 106 has a frequency in the GHz range, for example, a frequency of 1.0 GHz or higher (e.g., 1.2 GHz or higher, 1.4 GHz or higher, 1.6 GHz or higher, 2.0 GH or higher, 5.0 It can be modified to apply a sweep voltage to the ion trap 104 that repeats at or above GHz. With this modification of the ion trap 104 and voltage source 106, the mass spectrometer 100 can operate at pressures up to 1 atmosphere, greatly reducing the use of the pressure regulation subsystem 120. In some embodiments, it may be possible to remove the pressure regulation subsystem 120 from the analyzer 100, for example, so that the analyzer 100 is an analyzer without a pump.

  Several embodiments have been described. However, it will be understood that many modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims.

Claims (1)

An ion source;
An ion trap,
An ion detector;
A mass spectrometer including a gas pressure regulation subsystem,
During operation of the mass spectrometer,
The gas pressure regulation subsystem is configured to maintain a gas pressure between 100 millitorr and 100 torr in at least two of the ion source, the ion trap, and the ion detector;
The ion detector is a mass spectrometer configured to detect ions generated by the ion source according to a mass-to-charge ratio of the ions.