JP6167934B2 - Mass spectrometer - Google Patents

Description

  The present invention relates to a high-voltage power supply device and a mass spectrometer using the device, and more specifically, a high-voltage power supply device for applying a pulsed high voltage to a capacitive load and a mass using the device. The present invention relates to an analyzer.

  In a liquid chromatograph mass spectrometer (LC-MS), which combines a liquid chromatograph (LC) and a mass spectrometer (MS), the components in the sample solution eluted from the liquid chromatograph column can be measured at approximately atmospheric pressure. In order to perform ionization, an ion source using an atmospheric pressure ionization method such as an electrospray ionization (ESI) method or an atmospheric pressure chemical ionization (APCI) method is used. Since the ESI ion source and the APCI ion source are different in compounds that are easily ionized, the ionization method is usually selected depending on the type of sample to be analyzed and the purpose of analysis. In order to cope with this, an ion source having a structure capable of selectively performing ionization by the ESI method and ionization by the APCI method is known (see Patent Document 1, etc.).

  In recent years, a new atmospheric pressure ionization method has been developed and put into practical use in order to cope with diversification of samples to be analyzed or improvement in analysis accuracy and throughput. The probe electrospray ionization (PESI) method described in Non-Patent Document 1 is one of such methods. In the PESI method, for example, a needle electrode that can be moved up and down is lowered above the sample, and the tip of the needle electrode is brought into contact with the sample or slightly inserted, and a part of the sample is attached to the tip of the needle electrode. Let Thereafter, the needle electrode is pulled up and separated from the sample, and a high voltage is applied to the needle electrode from a high voltage power supply device. Then, a strong electric field acts on the sample at the tip of the needle electrode to cause an electrospray phenomenon, and sample molecules are ionized while being detached from the sample. The ions thus generated are collected and transported to a subsequent vacuum chamber for mass analysis.

  According to the PESI method, for example, a sample such as a biological section cut out from a biological tissue can be subjected to mass spectrometry without preprocessing. Further, for example, each time the stage on which the sample is placed is moved two-dimensionally, the sample is sampled by moving the needle electrode up and down and a high voltage is applied to the needle electrode, so that the two-dimensional mass of the sample is obtained. Distribution information can be obtained.

  When ionization by such PESI method and ionization by ESI method or APCI method described above are selectively performed, since these ionization methods all require a high voltage of several kV at the maximum, a high voltage power supply device is required. Sharing is advantageous in terms of cost, reduction in size and weight of the apparatus, and the like. However, in general, in an ESI ion source or an APCI ion source, a high voltage is continuously applied to a spray nozzle or the like in order to ionize sample components in a sample solution continuously supplied from a liquid chromatograph column or the like. On the other hand, in the PESI ion source that performs the repeated measurement as described above, it is necessary to turn on and off the high voltage applied to the needle electrode. Therefore, when ionizing by the PESI method, a high voltage switching circuit that switches a DC high voltage to generate a high voltage pulse is required.

JP-A-8-297112

Ogi Takeda and 7 others, “New Cancer Diagnosis Support Device Combining Mass Spectrometry and Statistical Learning Machines”, Shimadzu Critic Editorial Department, Shimadzu Criticism, Vol. 69, No. 3, No. 4, March 29, 2013 Issue

  In general, a semiconductor switching element such as a high breakdown voltage MOSFET is used for the high voltage switching circuit as described above. However, simply switching a high voltage output from a DC high voltage power source for an ESI ion source or an APCI ion source has the following problems.

  That is, in ionization by the ESI method or the APCI method, when a high voltage is applied to a spray nozzle or a needle electrode for corona discharge, a discharge current flows through a spray flow of a highly conductive sample solution. Therefore, in order to stabilize this discharge, a high resistance of several tens of MΩ is usually used as the output resistance of the DC high voltage power supply. In this configuration, for example, when the spray amount of the sample solution increases and the discharge current increases, the voltage drop due to the output resistance of the DC high-voltage power source increases. As a result, the voltage applied to the spray nozzle or the like of the ESI ion source is reduced, and the discharge can be stabilized.

On the other hand, when the ionization by PESI method for applying a high voltage in the atmosphere to the needle electrode the sample adhering to the surface, and the discharge current compared to the ESI ion source and APCI ion source is much smaller. Therefore, the needle electrode in the PESI ion source, that is, the load of the high-voltage power supply device can be regarded as a simple capacitance. This capacitance is mainly the stray capacitance of the high voltage cable line connecting the high voltage power supply device and the needle electrode. Although this is a small capacitance of about several tens of pF to several hundreds of pF, when such a capacitive load is connected to a high voltage power supply device having an output resistance of several tens MΩ as described above, the resistance and capacitance Due to the time constant of the RC circuit, the rise time of the high voltage pulse applied to the needle electrode is on the order of msec. When the time width of the high voltage pulse applied to the needle electrode is short, if the rise of the high voltage pulse is delayed, the time during which the high voltage is applied to the sample at the tip of the needle electrode is too short and the ion generation efficiency decreases. In extreme cases, the voltage required for electrospray may not be reached and ions may not be generated.

  The present invention has been made to solve these problems, and the object of the present invention is that the output resistance of the DC high-voltage power supply is large and the load to which the high-voltage pulse is applied is capacitive. Another object of the present invention is to provide a high-voltage power supply device including a high-voltage switching circuit that can supply a high-voltage pulse with good rising characteristics to a load, and a mass spectrometer using the device.

In order to solve the above problems, the present invention provides a high-voltage power supply apparatus that switches a voltage from a DC high-voltage power supply to generate a high-voltage pulse and supplies it to a capacitive load.
a) a first switch for opening and closing a line from the output end of the DC high-voltage power supply to the load;
b) a second switch for opening and closing between the output end of the first switch and the common line;
c) a capacitor connected between the input end of the first switch and the common line;
d) When applying the high voltage pulse to the load, switching the first switch from OFF to ON and switching the second switch from ON to OFF, and stopping the application of the high voltage pulse to the load A controller that switches the first switch from on to off and switches the second switch from off to on;
Immediately after switching the first and second switches to apply a high voltage pulse to the load, the charge held in the capacitor until immediately before is switched through the first switch that is turned on. To charge the capacity.

  In the high voltage power supply device according to the present invention, the first and second switches are high withstand voltage (that is, power) semiconductor switching elements, for example, power MOSFETs. The common line is typically a GND line. The capacitor may be a capacitor element, but a stray capacitance such as a cable line may be used.

  In the high voltage power supply device according to the present invention, when the first switch is in the off state and the second switch is in the on state under the control of the control unit, the load is connected to the common line through the second switch. The electric charge stored in the capacitor is discharged, and the potential of the load becomes equal to the potential of the common line. On the other hand, since the voltage from the DC high voltage power source is applied to the capacitor at this time, the capacitor is in a charged state. From this state, when the control unit switches the first switch on and the second switch off, first, the charge held in the capacitor until immediately before is supplied to the load capacitor through the first switch. Charged. Since the charge supply at this time is not affected by the output resistance of the DC high-voltage power supply, the voltage applied to the load quickly rises to a voltage corresponding to this charging.

Subsequently, a voltage from a DC high voltage power source is applied to the load through the first switch. The rise of this voltage becomes gradual due to the time constant of the RC circuit consisting of the output resistance of the DC high voltage power supply, the load capacitance and the capacitance of the capacitor. However, since the load capacitance is charged to some extent, The rise time up to the voltage value is surely shortened compared to the case where there is no charge by the capacitor. That is, in the high voltage power supply device according to the present invention, a high voltage pulse that rises quickly can be applied to the load.
Note that the polarity of the voltage by the DC high-voltage power supply may be positive or negative, and the rising of the voltage means a change when the absolute value of the voltage increases from a small state.

  The high-voltage power supply device according to the present invention can be used for various devices that require a high-voltage pulse having a voltage value of, for example, about several hundred V to several kV, or even higher. This is useful for a device that needs to increase the output resistance of a power supply and that needs to apply a high voltage pulse to a capacitive load. As described above, when performing ionization by the ESI method or the APCI method, it is necessary to apply a DC high voltage to the ion source that performs ionization through a large output resistance. On the other hand, when performing ionization by the PESI method It is necessary to apply a high voltage pulse to the capacitive load. Therefore, the high-voltage power supply device according to the present invention is suitable for a mass spectrometer equipped with an ion source that can be switched between ionization by the ESI method or APCI method and ionization by the PESI method.

  That is, the mass spectrometer according to the present invention using the high-voltage power supply device according to the present invention includes, as an ion source, at least one of an ion source by an ESI method or an ion source by an APCI method, and an ion source by a PESI method. A spray nozzle or the APCI method in which a needle electrode, which is a component of an ion source by the PESI method, is used as the load, and a voltage from the DC high-voltage power source is a component of the ion source by the ESI method It is characterized by being applied to a corona discharge needle electrode which is a constituent element of the ion source.

  Here, the ion source based on the PESI method includes a needle electrode and a moving unit that moves at least one of the needle electrode or the sample to attach the sample to the tip of the needle electrode. In this configuration, at least one of the needle electrode and the sample is moved by the moving unit, the tip of the needle electrode is brought into contact with or slightly inserted into the sample, and a part of the sample is attached to the tip of the needle electrode. After that, a high voltage pulse is applied to the needle electrode separated from the sample to ionize components in the sample adhering to the needle electrode. In the mass spectrometer according to the present invention, the rising of the high voltage pulse applied to the needle electrode at this time can be made quick, so it is necessary for electrospray even if the time width of the high voltage pulse is narrowed. A reliable voltage can be applied to the needle electrode. Thereby, the ion generation efficiency by the PESI method can be increased.

  According to the high-voltage power supply device according to the present invention, even if the output resistance of the direct-current high-voltage power supply that generates direct-current voltage is large, the high-voltage pulse applied to the capacitive load can be started up at high speed. Thereby, for example, even if the pulse width of the high voltage pulse is narrowed, a pulse having a predetermined voltage value (pulse height) can be reliably applied. Furthermore, the generation cycle of the high voltage pulse can be shortened thereby.

  Further, according to the mass spectrometer using the high voltage power supply device according to the present invention, a sufficient amount of ions can be generated even if the pulse width of the high voltage pulse applied to the needle electrode of the PESI ion source is narrowed. . Further, it is possible to shorten the repetition period of the mass spectrometry measurement using the PESI ion source and increase the measurement efficiency.

The schematic block diagram of one Example of the mass spectrometer which used the high voltage power supply device which concerns on this invention. The schematic block diagram of one Example of the high voltage power supply device which concerns on this invention. Operation | movement explanatory drawing of the high voltage power supply device of a present Example. The actual measurement figure of the output voltage waveform of the high voltage power supply device of a present Example.

Hereinafter, an embodiment of a high voltage power supply apparatus according to the present invention and an embodiment of a mass spectrometer using the apparatus will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an embodiment of a mass spectrometer using a high voltage power supply device according to the present invention.

  This mass spectrometer has a stepwise vacuum degree between an ionization chamber 1 that ionizes components in a sample under atmospheric pressure and an analysis chamber 4 that performs mass separation and detection of ions under high vacuum. This is a multistage differential exhaust system configuration including a plurality of (in this example, two) intermediate vacuum chambers 2 and 3 with an enhanced In FIG. 1, the PESI ionization unit A is provided in the ionization chamber 1 maintained at a substantially atmospheric pressure, but this ionization unit can be replaced with another ionization unit B such as an ESI ionization unit.

  The PESI ionization unit A includes a sample stage 8 on which a sample 9 is placed, a needle electrode 10 disposed in a space on the sample stage 8, and a nozzle 7 that ejects a solvent near the tip of the needle electrode 10 at a predetermined position. And including. The needle electrode 10 can be moved in the Z-axis direction in the figure by a Z-direction drive unit 12 including a motor, a speed reduction mechanism, or an actuator. A high voltage of about several kV at the maximum is applied from the high voltage generator 11 to the needle electrode 10. On the other hand, the sample stage 8 can be moved in the X-axis direction and the Y-axis direction in the figure by an XY direction drive unit 13 including a motor, a speed reduction mechanism, and the like. Thereby, when the needle electrode 10 is lowered, the position on the surface of the sample 9 where the tip of the needle electrode 10 contacts can be arbitrarily moved in the XY plane. A predetermined solvent such as water, alcohols, and acetonitrile is stored in the solvent container 5, and when the liquid feeding pump 6 is operated, the solvent sucked from the solvent container 5 by the pump 6 at a substantially constant flow rate from the nozzle 7. It is ejected as fine droplets.

The inside of the ionization chamber 1 and the inside of the first intermediate vacuum chamber 2 communicate with each other through a small-sized desolvation tube 14, and the gas in the ionization chamber 1 is removed from the desolvation tube 14 due to a pressure difference between both ends of the desolvation tube 14. Through and into the first intermediate vacuum chamber 2. In the first intermediate vacuum chamber 2, a plurality of disk-shaped electrode plates arranged along the ion optical axis C are used as one virtual rod electrode, and four virtual rods are arranged around the ion optical axis C. A first ion guide 15 called a Q array in which electrodes are arranged is installed. The first intermediate vacuum chamber 2 and the second intermediate vacuum chamber 3 communicate with each other through a small-diameter orifice formed at the top of the skimmer 16. In the second intermediate vacuum chamber 3, an octopole-type second ion guide 17 in which eight rod electrodes are arranged around the ion optical axis C is installed. In the analysis chamber 4 at the last stage, a quadrupole mass filter 18 in which four rod electrodes are arranged around the ion optical axis C, and an ion detector 19 that outputs a signal corresponding to the amount of ions that have reached. Is arranged. Although the description of the first ion guide 15, the second ion guide 17, the quadrupole mass filter 18, and the signal line is omitted, each part such as the desolvation tube 14 and the ion detector 19 includes a voltage generator. A predetermined voltage is applied from 20.

  The control unit 22 controls the high voltage generation unit 11, the Z direction driving unit 12, the XY direction driving unit 13, the voltage generation unit 20, and the like in order to perform mass analysis on the sample 9. Further, the detection signal from the ion detector 19 is input to the data processing unit 21 where it is converted into digital data and then predetermined data processing is executed. The control unit 22 is connected to an input unit 23 and a display unit 24 that serve as a user interface.

  In this mass spectrometer, a mass analysis operation when acquiring mass spectrum data for the target sample 9 will be schematically described. The sample 9 to be analyzed here is, for example, a cell tissue collected from a subject.

  As shown in FIG. 1, with the sample 9 placed on the sample stage 8, under the control of the control unit 22, the Z-direction drive unit 12 has the needle electrode 10 and its tip slightly on the upper surface of the sample 9. The needle electrode 10 is lowered to a predetermined position (solid line position in FIG. 1). As a result, a small part of the sample 9 adheres to the tip of the needle electrode 10. A sample on the sample stage 8 is denoted by reference numeral 9, and a sample attached to the needle electrode 10 is denoted by reference numeral 9a. By appropriately moving the sample stage 8 by the XY direction drive unit 13, the part where the sample 9 a is collected by the needle electrode 10 on the surface of the sample 9 can be arbitrarily changed.

  Thereafter, the high voltage generator 11 applies a predetermined high voltage pulse to the needle electrode 10 and at the same time, the solvent droplets refined from the nozzle 7 by the operation of the liquid feed pump 6 are ejected toward the tip of the needle electrode 10. Let The polarity of the high voltage applied to the needle electrode 10 depends on the type of component to be analyzed. When a high voltage pulse is applied to the tip of the needle electrode 10, a large electric field acts on the adhering sample 9a, and the sample 9a is detached while having a biased charge due to Coulomb repulsion or the like. In the process, sample molecules are ionized. The generated ions are sucked into the desolvation tube 14 along the gas flow generated by the pressure difference as described above, and sent into the first intermediate vacuum chamber 2.

  The sample 9a adhering to the needle electrode 10 is easy to dry, but by spraying a solvent from the nozzle 7, it can be ionized satisfactorily while dissolving the sample 9a on the surface of the needle electrode 10 or maintaining appropriate moisture. . In addition, since the electrospray can be performed slowly by supplying the solvent, even when the sample 9a includes a plurality of components, the plurality of components can be ionized without delay while delaying the ionization of the components that are easily ionized. Can do.

  The ions derived from the sample 9 a sent into the first intermediate vacuum chamber 2 are transported while being converged by a high-frequency electric field formed by the first ion guide 15, and sent to the second intermediate vacuum chamber 3 through the orifice at the top of the skimmer 16. . Further, the ions are sent to the analysis chamber 4 while being converged by a high frequency electric field formed by the second ion guide 17. A voltage obtained by superimposing a high frequency voltage on a DC voltage is applied from the voltage generator 20 to the quadrupole mass filter 18, and only ions having a mass-to-charge ratio m / z corresponding to the voltage are the length of the quadrupole mass filter 18. Ions passing through the axial space and other mass-to-charge ratio ions diverge midway. The voltage applied from the voltage generator 20 to the quadrupole mass filter 18 is scanned within a predetermined range, and the mass-to-charge ratio of ions that can pass through the quadrupole mass filter 18 is scanned within the predetermined range. . Therefore, ion intensity information in a predetermined mass range, that is, mass spectrum information can be obtained by measuring the intensity of ions that reach the ion detector 19 over time during one voltage scan. .

The data processing unit 21 collects the mass spectrum data as described above and stores it in the data storage device. The same mass-to-charge ratio range may be scanned a plurality of times, and the data obtained in each scan may be integrated for each mass-to-charge ratio to obtain mass spectrum data.
As described above, this mass spectrometer can obtain mass spectrum data of a very small specific portion on the sample 9. When it is desired to obtain mass spectrum data of different parts with respect to the same sample 9, the sample stage 8 is appropriately moved by the XY direction driving unit 13 and the needle electrode 10 is lowered by the Z direction driving unit 12 to thereby move the sample 9 Then, a part of the sample 9 is attached to the tip of the needle electrode 10 and ionization and mass spectrometry as described above may be performed.

As described above, the high voltage generator 11 applies a high voltage pulse to the needle electrode 10 during ionization. The high voltage generator 11 is an embodiment of the high voltage power supply device according to the present invention.
FIG. 2 is a schematic configuration diagram of the high voltage generator 11.
The high voltage generator 11 includes a DC high voltage power supply 110 that outputs a DC high voltage of about several kV at maximum (polarity can be switched between positive and negative) and a high voltage switching circuit 112. The DC high voltage power supply 110 is also used to apply a DC high voltage to an ESI ionization unit mounted in place of the PESI ionization unit A or an ionization unit B which is an APCI ionization unit. That is, the DC high voltage power supply 110 is shared by a plurality of ionization units. On the other hand, the high voltage switching circuit 112 is used only in the PESI ionization unit A.
For the reasons described above, the resistance value R1 of the output resistor 111 of the DC high voltage power supply 110 is several MΩ or more.

  The high voltage switching circuit 112 is a resistor 113 having one end connected to the input end 117 and the other end connected to GND in order to divide the DC high voltage input from the input end 117 and having a resistance value R2. A capacitor 114 having a capacitance C1 connected in parallel to the resistor 113, a first switch 115 having one end connected to the input end 117 and the other end connected to the output end 118, and one end connected to the output end 118. A second switch 116 having the other end connected to GND. Both the first switch 115 and the second switch 116 are high-voltage semiconductor switching elements such as power MOSFETs, and are driven so as to be switched on and off by a control signal from the control unit 22. The needle electrode 10 is connected to the output end 118 of the high voltage switching circuit 112 via a high voltage cable. Although this high voltage cable line has a stray capacitance, since this capacitance is the same as the load capacitance when viewed from the output end 118, it is shown as a load capacitance 100 having a capacitance C2 in FIG.

  The resistor 113 is not an essential component in principle. In this example, the maximum output voltage of the DC high-voltage power supply 110 is about 5 kV, whereas the withstand voltage of the first and second switches 115 and 116 is about 4 kV. The voltage applied to is suppressed. If the withstand voltage of the switches 115 and 116 is sufficiently high, or if the maximum output voltage itself of the DC high-voltage power supply 110 is low, the resistor 113 is unnecessary. In addition, the capacitor 114 is not an independent circuit element, and can be replaced by a stray capacitance such as a cable line connecting the DC high voltage power supply 110 and the high voltage switching circuit 112.

A characteristic operation of the high voltage generator 11 will be described with reference to FIG.
When the first switch 115 is on and the second switch 116 is off, a high voltage is applied from the high voltage generator 11 to the needle electrode 10. When the output voltage is turned off, the first switch 115 is switched from on to off and the second switch 116 is switched from off to on in accordance with an instruction from the control unit 22. Then, as shown in FIG. 3 (a), the other end of the load capacitor 100, one end of which is connected to GND, is connected to the GND through the second switch 116, so that the load capacitor 100 was charged until just before that. The electric charge is discharged through the second switch 116. As a result, the output voltage decreases in a short time, and the load, that is, the potential of the needle electrode 10 becomes the GND level. That is, the fall of the high voltage pulse is rapid.

  As a matter of course, when both switches 115 and 116 are turned on at the same time, the output of the DC high voltage power supply 110 is short-circuited. Therefore, in order to avoid this, both switches 115 and 116 are not turned on at the same time. The on / off switching timing is appropriately adjusted. The same applies to the next output voltage turn-on.

When the output voltage is turned on, the first switch 115 is switched from off to on and the second switch 116 is switched from on to off in accordance with an instruction from the control unit 22. The operation when the output voltage is turned on can be described in two stages.
Immediately before the output voltage is turned on, that is, when the two switches 115 and 116 are in the state shown in FIG. 3A, the voltage VA across the capacitor 114 is expressed by the following equation (1).
VA = {R2 / (R1 + R2)} VE (1)
Here, VE is an output voltage of the DC high voltage power supply 110. As described above, at this time, the voltage across the load capacitor 100 is 0V. When the output voltage is turned on from this state, as shown in FIG. 3B, the charge charged in the capacitor 114 moves to the load capacitor 100 in a short time through the first switch 115. The voltage VB across the capacitor 114 and the load capacitance 100 after the movement is expressed by the following equation (2).
VB = {C1 / (C1 + C2)} VA (2)
This is the first stage of the output voltage rising operation.

Next, as shown in FIG. 3 (c), both the capacitor 114 and the load capacitance 100 are charged by the voltage from the DC high voltage power supply 110, whereby the output voltage gradually rises with a time constant of R1 × (C1 + C2). To do. Finally, the steady voltage VA is reached. This is the second stage of the output voltage rising operation.
Now, if the output voltage Vo (t) in the second stage and the passing currents I1 and I2 are defined as shown in FIG.
VE = (I1 + I2) R1 + Vo (t) (3)
However, I1 = (C1 + C2) (dVo (t) / dt), I2 = Vo (t) / R2
It is expressed. When the differential equation (3) is solved under the initial condition Vo (t) = VB (where t = 0), equation (4) is obtained.
Vo (t) = VA [1- (C2 * P) exp {-Pt ((1 / R1) + (1 / R2))}] (4)
However, P = 1 / (C1 + C2)

FIG. 4 is a waveform obtained by actually measuring the voltage applied to the needle electrode of the PESI ion source by the circuit shown in FIG.
From this measured waveform, in the high voltage generator 11 of this embodiment, even if the output resistance of the DC high voltage power supply 110 is large and the load is capacitive, the rise of the high voltage pulse applied to the load can be accelerated. Can be confirmed.

  It should be noted that the above embodiment is an example of the present invention, and it is obvious that any modification, correction, or addition as appropriate within the scope of the present invention is included in the scope of the claims of the present application. For example, the high voltage power supply device of the above embodiment can be used not only for the power source of the ion source in the mass spectrometer, but also for various devices that require high voltage pulses.

DESCRIPTION OF SYMBOLS 1 ... Ionization chamber 5 ... Solvent container 6 ... Liquid feed pump 7 ... Nozzle 8 ... Sample stage 9 ... Sample 10 ... Needle electrode 11 ... High voltage generation part 12 ... Z direction drive part 13 ... XY direction drive part 22 ... Control Unit 100 ... Load capacity 110 ... DC high voltage power supply 111 ... Output resistance 112 ... High voltage switching circuit 113 ... Resistor 114 ... Capacitors 115, 116 ... Switch 117 ... Input end 118 ... Output end

Claims (1)

A voltage by the DC high voltage power supply to a high voltage power supply unit for supplying to the switching to a generated capacitive high voltage pulsed load,
a) a first switch for opening and closing a line from the output end of the DC high-voltage power supply to the load;
b) a second switch for opening and closing between the output end of the first switch and the common line;
c) a capacitor connected between the input end of the first switch and the common line;
d) When applying the high voltage pulse to the load, switching the first switch from OFF to ON and switching the second switch from ON to OFF, and stopping the application of the high voltage pulse to the load A controller that switches the first switch from on to off and switches the second switch from off to on;
Immediately after switching the first and second switches to apply a high voltage pulse to the load, the charge held in the capacitor until immediately before is switched through the first switch that is turned on. In a mass spectrometer using a high voltage power supply device that is charged to charge the capacity ,
The ion source includes at least one of an ion source based on an electrospray ionization method or an ion source based on an atmospheric pressure chemical ionization method, and an ion source based on a probe electrospray ionization method. The configuration of the ion source by the spray nozzle or the atmospheric pressure chemical ionization method in which the needle electrode, which is a component of the source, is used as the load, and the voltage from the DC high-voltage power source is a component of the ion source by the electrospray ionization method A mass spectrometer characterized by being applied to a corona discharge needle electrode as an element.

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