CN117690778A - Mass spectrometer ion transmission method and device - Google Patents
Mass spectrometer ion transmission method and device Download PDFInfo
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- CN117690778A CN117690778A CN202410151147.4A CN202410151147A CN117690778A CN 117690778 A CN117690778 A CN 117690778A CN 202410151147 A CN202410151147 A CN 202410151147A CN 117690778 A CN117690778 A CN 117690778A
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- 230000005540 biological transmission Effects 0.000 title claims abstract description 73
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Abstract
The invention discloses a mass spectrometer ion transmission method and a device, wherein ions are introduced into a vacuum side from an atmospheric pressure side by adopting a sample introduction channel, and the diameter of a sample introduction port of the sample introduction channel positioned on the atmospheric pressure side is smaller than that of a sample outlet positioned on the vacuum side; the transmission channel is funnel-shaped, the axis of the sample introduction channel and the axis of the transmission channel are arranged in an angle or parallel offset manner, the airflow carrying ions entering the vacuum cavity is blocked by the ion funnel assembly, the directional airflow of the gas is fully blocked and diffused, the gas is prevented from flowing into the cavity where the multipole rod assembly is positioned, and the vacuum load pressure of the cavity is relieved; the ion-carrying gas flow contains interfering particles, which are arranged in an angle or offset manner, the ion funnel component blocks the interfering particles, and charged ions to be analyzed are blocked in the funnel-shaped inner space under the pseudopotential well effect of the radio frequency electric field, focused into extremely fine ions and moved towards the outlet side, and cannot leak out of the ion funnel component or collide with the ion funnel component.
Description
Technical Field
The invention relates to the field of mass spectrometers, in particular to a mass spectrometer ion transmission method and a mass spectrometer ion transmission device.
Background
The mass spectrometer is an analytical instrument widely applied to the fields of environmental monitoring, food safety, drug research and development, material science, life science, petrochemical industry and the like. Of all mass spectrometry instruments, more than about half are atmospheric pressure ionization source mass spectrometers. Such mass spectrometry suffers from the problem of transferring charged ions from atmospheric pressure into a vacuum system for mass analysis. At present, a typical scheme of matching a vacuum small hole with a multipole rod or matching a capillary with an ion funnel is mostly adopted in a mass spectrometer as an ion transmission device under an atmospheric pressure-vacuum interface. The main direction of upgrading and upgrading the mass spectrum instrument is to improve the signal intensity and the signal-to-noise ratio of the instrument, reduce interference noise and the like.
In patent US6107628A, a method and apparatus for introducing ions and other charged particles generated at near atmospheric pressure into a vacuum region is disclosed, employing capillary injection, along with an ion funnel to achieve efficient ion focusing at vacuum pressures of 0.1-50 Torr. Compared with the traditional quadrupole rod scheme which is used for mTorr level and below, the ion funnel can realize ion focusing under higher pressure, so that the sample injection amount can be increased by improving the size of the sample injection hole, the signal intensity is improved, and the ion funnel has better advantages. However, the scheme does not consider the higher vacuum load of the strong directional air flow generated by the direct sample injection of the capillary to the next stage vacuum chamber of the ion funnel vacuum chamber, and also does not consider the interference problem of neutral particles in the ion flow to links such as a subsequent mass analyzer, a detector and the like.
In patent US9240310B2, a method and apparatus are disclosed for improving ion entry into a mass spectrometer, a tapered feed tube, having higher ion capture and transport efficiency and better ion flow concentration than conventional capillary feed tubes. Especially has obvious advantages for application scenes such as nano-liter electrospray and the like, and can improve the signal intensity to a certain extent. However, the scheme does not consider the high vacuum load of the strong directional air flow generated by the direct sample injection of the sample injection tube on the subsequent ion transmission or the mass analysis vacuum chamber, and also does not consider the interference problem of neutral particles in the ion flow on the subsequent mass analyzer, detector and other links.
Disclosure of Invention
In order to overcome the defects in the prior art, one of the purposes of the invention is to provide a mass spectrometer ion transmission method which can transfer charged ions from atmospheric pressure to a vacuum system and can avoid the influence of directional air flow generated by sample injection and neutral particles on subsequent analysis.
In order to overcome the defects in the prior art, the second object of the invention is to provide an ion transmission device of a mass spectrometer, which can transfer charged ions from atmospheric pressure to a vacuum system and can avoid the influence of directional air flow generated by sample injection and neutral particles on subsequent analysis.
One of the purposes of the invention is realized by adopting the following technical scheme:
a method of mass spectrometer ion transport comprising the steps of:
the method comprises the steps that ions enter a vacuum side from an atmospheric pressure side through a sample injection channel of a conical tube, wherein the sample injection channel is conical, and the diameter of a sample injection port of the sample injection channel positioned on the atmospheric pressure side is smaller than that of a sample outlet positioned on the vacuum side;
an ion funnel assembly is formed by stacking a plurality of lens pole pieces, the ion funnel assembly is provided with a transmission channel, the inner diameters of partial lens pole pieces close to the sample introduction channel are the same to form a straight cylindrical ion channel, so that ions can be conveniently captured into the ion funnel assembly in a large range, the inner diameters of partial lens pole pieces far away from the sample introduction channel are gradually reduced along the ion movement direction, and the funnel-shaped ion channel is formed, so that ions can be conveniently focused gradually to form finer ion beams, and the finer ion beams pass through the last lens pole piece with the smallest inner diameter and enter the multipole rod assembly;
the axis of the sample injection channel and the axis of the transmission channel are arranged in an angle or in parallel offset manner;
the sample injection channel is provided with direct current voltage V1, a plurality of lens pole pieces are provided with direct current voltage and radio frequency voltage, wherein two adjacent lens pole pieces are provided with radio frequency voltage with opposite phases, the direct current voltage on the lens pole pieces gradually transits from V2 to V3 along the ion movement direction, and the multipole rod component is provided with direct current voltages V4, V1, V2, V3 and V4 which are increased or decreased in a unidirectional way so as to drive ions from the sample injection channel to the multipole rod component through the transmission channel.
Further, when the axis of the sample injection channel and the axis of the transmission channel are arranged at an angle, the included angle between the axis of the sample injection channel and the axis of the transmission channel is 0.1-30 degrees.
Further, when the axis of the sample injection channel and the axis of the transmission channel are arranged in parallel in an offset manner, the offset distance between the axis of the sample injection channel and the axis of the transmission channel is 1-10mm.
Further, the inner diameter of the sample inlet channel is 0.1-5mm, and the taper of the sample inlet channel is 0.3-10 degrees.
Further, the mass spectrometer ion transfer method further comprises a heating step, wherein the heating step specifically comprises the following steps: and heating the sample injection channel to desolvate and dissociate the solvent ion clusters entering the sample injection channel to form charged ions.
Further, the multipole rod assembly is applied with a radio frequency voltage, wherein the phases of the radio frequency voltages applied between two adjacent rods are opposite.
The second purpose of the invention is realized by adopting the following technical scheme:
the ion transmission device of the mass spectrometer comprises a vacuum cavity and an ion funnel assembly arranged in the vacuum cavity, the ion transmission device of the mass spectrometer further comprises a sample injection assembly and a multipole rod assembly, the sample injection assembly is arranged on one side of the vacuum cavity, the multipole rod assembly is arranged in the vacuum cavity, the ion funnel assembly is arranged between the sample injection assembly and the multipole rod assembly, the sample injection assembly comprises a conical tube, the conical tube is provided with a sample injection channel, the sample injection channel is conical, the diameter of a sample injection port of the sample injection channel on the atmospheric pressure side is smaller than that of a sample outlet on the vacuum side, the ion funnel assembly is provided with a transmission channel, the width of one side of the sample injection channel is close to the multipole rod assembly and gradually reduces to form a funnel-shaped ion channel, and the axis of the sample injection channel and the axis of the transmission channel are arranged in an angle or in parallel offset mode.
Further, the ion funnel assembly comprises a plurality of lens pole pieces, the lens pole pieces are stacked, each lens pole piece is provided with an inner hole, the inner holes of the lens pole pieces form the transmission channel, the inner diameters of the lens pole pieces close to the sample introduction channel are the same to form a straight cylindrical ion channel, and the inner diameters of the lens pole pieces far away from the sample introduction channel are gradually reduced along the ion movement direction to form a funnel-shaped ion channel.
Further, when the axis of the sample injection channel and the axis of the transmission channel are arranged at an angle, the included angle between the axis of the sample injection channel and the axis of the transmission channel is 0.1-30 degrees.
Further, when the axis of the sample injection channel and the axis of the transmission channel are arranged in parallel in an offset manner, the offset distance between the axis of the sample injection channel and the axis of the transmission channel is 1-10mm.
Compared with the prior art, the ion transmission method of the mass spectrometer has the advantages that ions enter the vacuum side from the atmospheric pressure side through the sample injection channel of the conical tube, and the diameter of the sample injection port of the sample injection channel positioned on the atmospheric pressure side is smaller than that of the sample outlet positioned on the vacuum side; the inner diameters of the partial lens pole pieces close to the sample introduction channel are the same to form a straight cylindrical ion channel, so that ions can be conveniently captured into the ion funnel assembly in a large range, the inner diameters of the partial lens pole pieces far from the sample introduction channel are gradually reduced along the ion movement direction, and the funnel-shaped ion channel is formed, so that the ions can be conveniently focused gradually to form finer ion beams, and the finer ion beams enter the multipole rod assembly through the last lens pole piece with the smallest inner diameter; the axis of the sample injection channel and the axis of the transmission channel are arranged in an angle or in parallel offset; through the design, the air flow carrying ions entering the vacuum cavity through the conical sample injection pipe in the atmospheric pressure environment can be blocked by the ion funnel assembly, so that strong directional flow in the air flow is relieved, the directional flow is fully blocked and diffused, and the air flow is prevented from flowing into the cavity where the multipole rod assembly is located, and therefore the vacuum load pressure of the cavity where the multipole rod assembly is located is relieved; the ion-carrying airflow also contains some neutral particles and other interference particles, and the angle arrangement or the offset arrangement can be used for blocking the particles by the ion funnel assembly, and charged ions to be analyzed can be blocked in the inner space of the funnel shape under the pseudopotential well effect of the radio frequency electric field of the ion funnel assembly and cannot leak out of the ion funnel assembly or collide with the ion funnel assembly, focused into extremely fine ion flow and move towards the outlet side of the ion funnel assembly along the funnel shape.
Drawings
FIG. 1 is a flow chart of a mass spectrometer ion transport method of the present invention;
FIG. 2 is a perspective view of a first embodiment of the ion transport device of the mass spectrometer of the present invention;
FIG. 3 is a perspective cross-sectional view of the ion transport device of the mass spectrometer of FIG. 2;
FIG. 4 is a cross-sectional view of a tapered tube of the ion transport device of the mass spectrometer of FIG. 2;
FIG. 5 is a cross-sectional view of an ion funnel assembly of the ion transport device of the mass spectrometer of FIG. 2;
FIG. 6 is a partial structural cross-sectional view of the ion transport device of the mass spectrometer of FIG. 2;
FIG. 7 is a cross-sectional view of a second embodiment of the ion transport device of the mass spectrometer of the present invention;
fig. 8 is a simulation diagram of ion focusing and transmission when the axis of the sample channel and the axis of the transmission channel are arranged offset in the ion transmission device of the mass spectrometer.
In the figure: 10. a sample injection assembly; 11. a housing; 12. a conical tube; 120. a mounting part; 121. an extension; 122. a sample introduction channel; 20. a vacuum chamber; 30. an ion funnel assembly; 31. a lens pole piece; 32. a mounting column; 33. a circuit board; 34. a transmission channel; 40. a multipole rod assembly.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or be present as another intermediate element through which the element is fixed. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1 to 7, the ion transmission method of the mass spectrometer of the present invention comprises the following steps:
by using the sample introduction channel 122 of the conical tube 12 to enable ions to enter the vacuum side from the atmospheric pressure side, the sample introduction channel 122 is conical, and the diameter of the sample introduction port of the sample introduction channel 122 positioned on the atmospheric pressure side is smaller than that of the sample outlet positioned on the vacuum side;
the ion funnel assembly 30 is formed by stacking a plurality of lens pole pieces 31, the ion funnel assembly 30 is provided with a transmission channel 34, the inner diameters of the partial lens pole pieces 31 close to the sample introduction channel 122 are the same to form a straight cylindrical ion channel, so that ions can be conveniently captured into the ion funnel assembly 30 in a large range, the inner diameters of the partial lens pole pieces 31 far away from the sample introduction channel 122 are gradually reduced along the ion movement direction, and the funnel-shaped ion channel is formed, so that the ions can be conveniently focused gradually to form a thinner ion beam to pass through the last lens pole piece 31 with the smallest inner diameter and enter the multipole rod assembly 40;
the axis of the sample introduction channel 122 is arranged at an angle or in parallel offset with the axis of the transmission channel 34;
the direct current voltage V1 is applied to the sample injection channel 122, the direct current voltage and the radio frequency voltage are applied to the plurality of lens pole pieces 31, the radio frequency voltages with opposite phases are applied to the adjacent two lens pole pieces 31, the direct current voltage on the plurality of lens pole pieces 31 gradually transits from V2 to V3 along the ion movement direction, the direct current voltage V4 and the radio frequency voltage are applied to the multipole rod assembly 40, the radio frequency voltages with opposite phases are applied between the adjacent two rods, and the V1, V2, V3 and V4 are increased or decreased in a unidirectional way according to the positive and negative charge conditions of charged ions so as to drive the ions from the sample injection channel 122 to the multipole rod assembly 40 through the transmission channel 34.
In particular, the tapered tube 12 can achieve equivalent ion capturing efficiency with a smaller bore diameter (taking the smallest inner diameter value of the tapered tube 12) by using a smaller bore diameter or a capillary tube with a common circular cross section. Smaller bore diameters result in less vacuum load pressure than larger bore holes or capillaries due to their poorer vacuum. Meanwhile, the ion beam divergence of the conical capillary tube is smaller, and the conical capillary tube has better concentration. The sample introduction passage 122 of the conical tube 12 has a smaller inner diameter on the ion inlet side and a larger inner diameter on the ion outlet side. Typically, the minimum inner diameter of the tapered tube 12 is between 0.1-5mm and the taper of the feed channel 122 is between 0.3-10 °. Preferably, the minimum inner diameter of the conical tube 12 is between 0.3 and 1.5mm, and the taper of the sample introduction channel 122 is between 0.5 and 2 degrees. The sample introduction assembly 10 has a heating function near the sample introduction channel 122 of the conical tube 12, so that the solvent ion clusters can be desolvated efficiently and dissociated to form charged ions. The sample introduction channel 122 of the conical tube 12 is applied with a dc voltage V1.
Specifically, the ion funnel assembly 30 is composed of about 20-100 lens pole pieces 31 stacked together. The lens sheet 31 has a dc voltage and a radio frequency voltage applied thereto. Wherein the amplitude of the radio frequency voltage is 20-400V, the frequency is 0.1MHz-5MHz, and the preferred frequency is 0.5-2 MHz. And applying radio frequency voltages with opposite phases between adjacent pole pieces. The 10-50 lens pole pieces 31 near the ion inlet side have the same inner diameter so as to form a section of straight cylindrical ion channel, thereby facilitating the capture of ions in a large range inside the ion funnel. The inner diameter of the 10-50 lens pole pieces 31 near one side of the ion outlet is gradually reduced along with the movement direction of ions so as to form a section of funnel-shaped ion channel, so that ions can be conveniently focused gradually inside the ion funnel to form a thinner ion beam, and the ion beam can smoothly pass through the inner hole of the last lens with the smallest inner diameter in the ion funnel and enter the second-stage ion transmission structure. The dc voltage on lens piece 31 generally gradually transitions from ion entrance side dc voltage V2 to ion exit side voltage V3.
The multipole rod assembly 40 is a second-stage ion transmission structure, and the multipole rod assembly 40 is formed by arranging a group of even number of parallel or conical conductive rods, wherein the conductive rods are any one or more of conductive metal rods, ceramic rods plated with conductive layers or quartz rods. The multipole rod assembly 40 has a radio frequency voltage and a direct current voltage applied thereto. Wherein the amplitude of the radio frequency voltage is 20-4000V, the frequency is 0.1MHz-5MHz, and the preferred frequency is 0.5-2 MHz. And a radio frequency voltage with opposite phase is applied between two adjacent rods. The metal rod is applied with a direct voltage V4. Preferably, multipole rod assemblies 40 generally employ a quadrupole rod structure, a hexapole rod structure, or an octapole rod structure.
For each of the dc voltages V1, V2, V3, V4 on the sample injection assembly 10, the ion funnel assembly 20, and the multipole rod assembly 40, the voltage is generally increased or decreased unidirectionally, depending primarily on the charge properties of the ions being analyzed. For positive ions, the values of V1, V2, V3 and V4 are generally set in a unidirectional decreasing manner, so that the positive ions actively move to the rear stage under the action of an electric field force in a gradually decreasing potential field. For negative ions, the values of V1, V2, V3 and V4 are generally set according to the unidirectional increasing values, so that the negative ions actively move to the rear stage under the action of an electric field force in a gradually increasing potential field.
The vacuum chamber 20 is used for isolating an internal vacuum environment from an external atmospheric pressure environment. The chamber section in which the ion funnel assembly 20 is typically located has a vacuum of 1-10Torr and a pumping speed in the range of 10-200 m 3 Mechanical pump implementation of/h; the chamber section in which multipole rod assembly 40 is located is evacuated to a vacuum of 1-10mTorr, typically using a turbo molecular pump with a pumping speed in the range of 10-1000L/s.
The axis of the sample introduction channel 122 in this application is disposed at an angle or parallel offset from the axis of the transfer channel 34. When the axis of the sample introduction channel 122 is disposed at an angle to the axis of the transmission channel 34, the angle between the axis of the sample introduction channel 122 and the axis of the transmission channel 34 is 0.1-30 °. The preferred range is between 1-5 deg.. When the axis of the sample introduction channel 122 is offset from the axis of the transfer channel 34 in parallel, the offset distance between the axis of the sample introduction channel 122 and the axis of the transfer channel 34 is 1-10mm. The preferred range is between 2-5 mm. When the axis of the sample introduction channel 122 is offset from the axis of the transmission channel 34, the simulation effect of ion focusing and transmission is shown in fig. 8. The advantages of such an arrangement are: 1) The airflow carrying ions entering the vacuum cavity 20 through the conical tube 12 of the sample injection assembly 10 in the atmospheric pressure environment is blocked by the ion funnel assembly 30, so that strong directional flow in the airflow is relieved, the directional flow is fully blocked and diffused, and the airflow is prevented from flowing into the cavity where the multipole rod assembly 40 is positioned, and thus the vacuum load pressure of the cavity where the multipole rod assembly 40 is positioned is relieved; 2) The ion-carrying gas flow also contains some neutral particles and other interference particles, and the arrangement of the angle arrangement or the parallel offset arrangement can block the particles by the ion funnel assembly 30, while charged ions to be analyzed can be blocked in the inner space of the funnel shape under the pseudopotential well effect of the radio frequency electric field of the ion funnel assembly 30 and cannot leak out of the ion funnel assembly 30 or collide onto the ion funnel assembly 30, focused into extremely fine ion flow and move towards the outlet side of the ion funnel assembly 30 along the funnel shape.
The invention also relates to a mass spectrometer ion transmission device for implementing the mass spectrometer ion transmission method, which comprises a sample injection assembly 10, a vacuum cavity 20, an ion funnel assembly 30 and a multipole rod assembly 40.
The sample injection assembly 10 is located on the atmospheric pressure side of the ion transport device of the mass spectrometer, and the sample injection assembly 10 comprises a housing 11 and a conical tube 12 mounted on the housing 11. The conical tube 12 is provided with a sample introduction passage 122, the sample introduction passage 122 extending from the atmospheric pressure side to the vacuum side. Specifically, the conical tube 12 includes a mounting portion 120 and an extension portion 121 extending from the mounting portion 120, the outer surface of the mounting portion 120 is tapered, and the extension portion 121 is cylindrical. The sample channel 122 penetrates through the mounting portion 120 and the extending portion 121, the sample channel 122 is integrally tapered, and the diameter of a sample inlet of the sample channel 122 on the atmospheric pressure side is smaller than that of a sample outlet on the vacuum side. The minimum inner diameter of the conical tube 12 is between 0.1 and 5mm, and the taper of the sample introduction channel 122 is between 0.3 and 10 degrees. Preferably, the minimum inner diameter of the conical tube 12 is between 0.3 and 1.5mm, and the taper of the sample introduction channel 122 is between 0.5 and 2 degrees. The design enables the tapered tube 12 to achieve equivalent ion capturing efficiency with a smaller bore diameter (taking the smallest inner diameter value of the tapered tube 12) by using a smaller bore diameter or a common circular cross-section capillary. Smaller bore diameters result in less vacuum load pressure than larger bore holes or capillaries due to their poorer vacuum. Meanwhile, the ion beam divergence of the conical capillary tube is smaller, and the conical capillary tube has better concentration.
The vacuum chamber 20 is used to isolate the internal vacuum environment from the external atmospheric pressure environment. Specifically, the vacuum cavity 20 is of a hollow structure, and one side of the vacuum cavity 20 is in sealing connection with the housing 11 of the sample injection assembly 10. The entire vacuum chamber 20 extends in the direction of ion movement (the extending direction of the sample introduction passage 122). The chamber section in which the ion funnel assembly 20 is located has a vacuum of 1-10Torr and a pumping speed in the range of 10-200 m 3 Mechanical pump implementation of/h; the chamber section in which multipole rod assembly 40 is located is evacuated to a vacuum of 1-10mTorr, typically using a turbo molecular pump with a pumping speed in the range of 10-1000L/s.
The ion funnel assembly 30 includes a plurality of lens pole pieces 31, a mounting post 32, and a circuit board 33, the plurality of lens pole pieces 31 being mounted on the mounting post 32 and stacked one on another. Circuit board 33 is mounted to lens sheet 31 and applies a voltage to lens sheet 31. Specifically, each lens sheet 31 is provided with an inner hole, and the inner holes of the plurality of lens sheets 31 form a transmission channel 34. The inner diameter of the part of the lens pole piece 31 close to the sample introduction channel 122 is the same to form a straight cylindrical ion channel, and the inner diameter of the part of the lens pole piece 31 far from the sample introduction channel 122 is gradually reduced along the ion movement direction to form a funnel-shaped ion channel. Specifically, the ion funnel assembly 30 is composed of about 20-100 lens pole pieces 31 stacked together. The lens sheet 31 has a dc voltage and a radio frequency voltage applied thereto. Wherein the amplitude of the radio frequency voltage is 20-400V, the frequency is 0.1MHz-5MHz, and the preferred frequency is 0.5-2 MHz. And applying radio frequency voltages with opposite phases between adjacent pole pieces. The 10-50 lens pole pieces 31 near the ion inlet side have the same inner diameter so as to form a section of straight cylindrical ion channel, thereby facilitating the capture of ions in a large range inside the ion funnel. The inner diameter of the 10-50 lens pole pieces 31 near one side of the ion outlet is gradually reduced along with the movement direction of ions so as to form a section of funnel-shaped ion channel, so that ions can be conveniently focused gradually inside the ion funnel to form a thinner ion beam, and the ion beam can smoothly pass through the inner hole of the last lens with the smallest inner diameter in the ion funnel and enter the second-stage ion transmission structure. The dc voltage on lens piece 31 generally gradually transitions from ion entrance side dc voltage V2 to ion exit side voltage V3.
With continued reference to fig. 6, in the first embodiment, the axis of the sample channel 122 is offset from the axis of the transmission channel 34 in parallel, and the offset distance between the axis of the sample channel 122 and the axis of the transmission channel 34 is 1-10mm. The preferred range is between 2-5 mm.
With continued reference to fig. 7, in the second embodiment, the axis of the sample channel 122 is disposed at an angle to the axis of the transmission channel 34, and the angle between the axis of the sample channel 122 and the axis of the transmission channel 34 is 0.1-30 °. The preferred range is between 1-5 deg..
The parallel offset arrangement or the angular arrangement has the following advantages: 1) The airflow carrying ions entering the vacuum cavity 20 through the conical tube 12 of the sample injection assembly 10 in the atmospheric pressure environment is blocked by the ion funnel assembly 30, so that strong directional flow in the airflow is relieved, the directional flow is fully blocked and diffused, and the airflow is prevented from flowing into the cavity where the multipole rod assembly 40 is positioned, and thus the vacuum load pressure of the cavity where the multipole rod assembly 40 is positioned is relieved; 2) The ion-carrying gas flow also contains some neutral particles and other interference particles, such as the neutral particles, and the like, and the particles can be blocked by the ion funnel assembly 30 in an angle arrangement or an offset arrangement, and charged ions to be analyzed can be blocked in the inner space of the funnel shape under the pseudopotential well effect of the radio frequency electric field of the ion funnel assembly 30 and cannot leak out of the ion funnel assembly 30 or collide onto the ion funnel assembly 30, focused into a very fine ion flow, and move towards the outlet side of the ion funnel assembly 30 along the funnel shape.
The multipole rod assembly 40 is a second-stage ion transmission structure, and the multipole rod assembly 40 is formed by arranging a group of even number of parallel or conical conductive rods, and adopting any one or more of conductive metal rods, ceramic rods or quartz rods plated with conductive layers, and the like. The multipole rod assembly 40 has a radio frequency voltage and a direct current voltage applied thereto. Wherein the amplitude of the radio frequency voltage is 20-4000V, the frequency is 0.1MHz-5MHz, and the preferred frequency is 0.5-2 MHz. And a radio frequency voltage with opposite phase is applied between two adjacent rods. The metal rod is applied with a direct voltage V4. Preferably, multipole rod assemblies 40 generally employ a quadrupole rod structure, a hexapole rod structure, or an octapole rod structure.
For each of the dc voltages V1, V2, V3, V4 on the sample injection assembly 10, the ion funnel assembly 20, and the multipole rod assembly 40, the voltage is generally increased or decreased unidirectionally, depending primarily on the charge properties of the ions being analyzed. For positive ions, the values of V1, V2, V3 and V4 are generally set in a unidirectional decreasing manner, so that the positive ions actively move to the rear stage under the action of an electric field force in a gradually decreasing potential field. For negative ions, the values of V1, V2, V3 and V4 are generally set according to the unidirectional increasing values, so that the negative ions actively move to the rear stage under the action of an electric field force in a gradually increasing potential field.
The ion transmission device of the mass spectrometer is mainly used in an atmospheric pressure ionization source mass spectrometer, and in the process of transferring charged ions from an atmospheric pressure environment to a mass analyzer in a vacuum environment, the related multistage differential vacuum and efficient ion transmission links are adopted. This solution is clearly different from the solutions used in the existing commercial instruments or those already existing in the existing patents. The scheme has the characteristics of simple structure, high ion capturing efficiency, low vacuum load pressure, low neutral particle interference and the like. The low vacuum load pressure is beneficial to further improving the size of the opening of the sample feeding part so as to increase the sample feeding amount, thereby improving the signal strength. Therefore, the method and the device can be used for remarkably improving the signal strength, reducing noise and improving the signal to noise ratio, and have higher practical value and industrialization value.
The foregoing examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, it is possible to make several modifications and improvements without departing from the concept of the present invention, which are equivalent to the above embodiments according to the essential technology of the present invention, and these are all included in the protection scope of the present invention.
Claims (10)
1. A method of ion transport for a mass spectrometer comprising the steps of:
the method comprises the steps that ions enter a vacuum side from an atmospheric pressure side through a sample injection channel of a conical tube, wherein the sample injection channel is conical, and the diameter of a sample injection port of the sample injection channel positioned on the atmospheric pressure side is smaller than that of a sample outlet positioned on the vacuum side;
an ion funnel assembly is formed by stacking a plurality of lens pole pieces, the ion funnel assembly is provided with a transmission channel, the inner diameters of partial lens pole pieces close to the sample introduction channel are the same to form a straight cylindrical ion channel, so that ions can be conveniently captured into the ion funnel assembly in a large range, the inner diameters of partial lens pole pieces far away from the sample introduction channel are gradually reduced along the ion movement direction, and the funnel-shaped ion channel is formed, so that ions can be conveniently focused gradually to form finer ion beams, and the finer ion beams pass through the last lens pole piece with the smallest inner diameter and enter the multipole rod assembly;
the axis of the sample injection channel and the axis of the transmission channel are arranged in an angle or in parallel offset manner;
the sample injection channel is provided with direct current voltage V1, a plurality of lens pole pieces are provided with direct current voltage and radio frequency voltage, wherein two adjacent lens pole pieces are provided with radio frequency voltage with opposite phases, the direct current voltage on the lens pole pieces gradually transits from V2 to V3 along the ion movement direction, and the multipole rod component is provided with direct current voltages V4, V1, V2, V3 and V4 which are increased or decreased in a unidirectional way so as to drive ions from the sample injection channel to the multipole rod component through the transmission channel.
2. The method of mass spectrometer ion transport according to claim 1, wherein: when the axis of the sample introduction channel and the axis of the transmission channel are arranged at an angle, the included angle between the axis of the sample introduction channel and the axis of the transmission channel is 0.1-30 degrees.
3. The method of mass spectrometer ion transport according to claim 1, wherein: when the axis of the sample injection channel and the axis of the transmission channel are arranged in parallel in an offset mode, the offset distance between the axis of the sample injection channel and the axis of the transmission channel is 1-10mm.
4. The method of mass spectrometer ion transport according to claim 1, wherein: the inner diameter of the sample inlet channel is 0.1-5mm, and the taper of the sample inlet channel is 0.3-10 degrees.
5. The method of mass spectrometer ion transport according to claim 1, wherein: the mass spectrometer ion transmission method further comprises a heating step, wherein the heating step specifically comprises the following steps: and heating the sample injection channel to desolvate and dissociate the solvent ion clusters entering the sample injection channel to form charged ions.
6. The method of mass spectrometer ion transport according to claim 1, wherein: the multipole rod assembly is applied with a radio frequency voltage, wherein the phases of the radio frequency voltages applied between two adjacent rods are opposite.
7. A mass spectrometer ion transfer device for performing the mass spectrometer ion transfer method of any of claims 1-6, said mass spectrometer ion transfer device comprising a vacuum chamber and an ion funnel assembly mounted within said vacuum chamber, characterized in that: the ion transmission device of the mass spectrometer further comprises a sample injection assembly and a multipole rod assembly, the sample injection assembly is arranged on one side of the vacuum cavity, the multipole rod assembly is arranged inside the vacuum cavity, the ion funnel assembly is positioned between the sample injection assembly and the multipole rod assembly, the sample injection assembly comprises a conical tube, the conical tube is provided with a sample injection channel, the sample injection channel is conical, the diameter of the sample injection port of the sample injection channel positioned on the atmospheric pressure side is smaller than that of the sample outlet positioned on the vacuum side, the ion funnel assembly is provided with a transmission channel, the transmission channel is close to the sample injection channel, the width of one side of the transmission channel is equal to that of the multipole rod assembly, the width of one side of the transmission channel is close to the multipole rod assembly, the width of the transmission channel is gradually reduced to form a funnel-shaped ion channel, and the axis of the sample injection channel is in angle setting or parallel offset setting.
8. The mass spectrometer ion transfer device of claim 7, wherein: the ion funnel assembly comprises a plurality of lens pole pieces, wherein each lens pole piece is stacked, each lens pole piece is provided with an inner hole, the inner holes of the plurality of lens pole pieces form the transmission channel, the inner diameters of the lens pole pieces close to the sample injection channel are the same to form a straight cylindrical ion channel, and the inner diameters of the lens pole pieces far away from the sample injection channel are gradually reduced along the ion movement direction to form a funnel-shaped ion channel.
9. The mass spectrometer ion transfer device of claim 7, wherein: when the axis of the sample introduction channel and the axis of the transmission channel are arranged at an angle, the included angle between the axis of the sample introduction channel and the axis of the transmission channel is 0.1-30 degrees.
10. The mass spectrometer ion transfer device of claim 7, wherein: when the axis of the sample injection channel and the axis of the transmission channel are arranged in parallel in an offset mode, the offset distance between the axis of the sample injection channel and the axis of the transmission channel is 1-10mm.
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| US6107628A (en) * | 1998-06-03 | 2000-08-22 | Battelle Memorial Institute | Method and apparatus for directing ions and other charged particles generated at near atmospheric pressures into a region under vacuum |
| US20140217281A1 (en) * | 2013-02-01 | 2014-08-07 | The Rockefeller University | Method and apparatus for improving ion transmission into a mass spectrometer |
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| CN211654766U (en) * | 2020-04-02 | 2020-10-09 | 昆山聂尔精密仪器有限公司 | Miniaturized mass spectrometer |
| CN115360077A (en) * | 2022-08-18 | 2022-11-18 | 天津国科医疗科技发展有限公司 | Ion funnel device for mass spectrometer vacuum interface |
| CN116598188A (en) * | 2022-11-04 | 2023-08-15 | 北京理工大学 | Gradual change multipole rod ion guiding device and mass spectrometry system thereof |
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| US6107628A (en) * | 1998-06-03 | 2000-08-22 | Battelle Memorial Institute | Method and apparatus for directing ions and other charged particles generated at near atmospheric pressures into a region under vacuum |
| US20140217281A1 (en) * | 2013-02-01 | 2014-08-07 | The Rockefeller University | Method and apparatus for improving ion transmission into a mass spectrometer |
| CN105679637A (en) * | 2014-12-03 | 2016-06-15 | 布鲁克·道尔顿公司 | Atmospheric pressure ion source interface of mass spectrometer |
| CN211654766U (en) * | 2020-04-02 | 2020-10-09 | 昆山聂尔精密仪器有限公司 | Miniaturized mass spectrometer |
| CN115360077A (en) * | 2022-08-18 | 2022-11-18 | 天津国科医疗科技发展有限公司 | Ion funnel device for mass spectrometer vacuum interface |
| CN116598188A (en) * | 2022-11-04 | 2023-08-15 | 北京理工大学 | Gradual change multipole rod ion guiding device and mass spectrometry system thereof |
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