Ion Analyzer

Abstract

The present invention relates to an ion analysis device (2), comprising: a power supply circuit (26) having a power supply connection portion (261), a first electrode connection portion (262), a first resistance element (263), a second electrode connection portion (264), a second resistance element (265), and a ground portion connected in series; a power supply (P) connected to the power supply connection portion (261) and outputting a DC voltage of both positive and negative polarities; a first voltage supply electrode (23) connected to the first electrode connection portion (262); and a second voltage supply electrode (24) connected to the second electrode connection portion (264). In particular, it can preferably be used as an ion analysis device for applying voltages to a repulsion electrode (23) and a focusing electrode (24) of an ionization chamber (20) of a mass analysis device equipped with an ESI source (21).

Description

Technical Field

[0001] The present invention relates to an ion analysis device. Background Art

[0002] As one of the devices for analyzing substances contained in a liquid sample, there is a liquid chromatography mass spectrometry device. In the liquid chromatography mass spectrometry device, a liquid sample is introduced into a chromatographic column of the liquid chromatography as the mobile phase flows, and a target substance is separated from other substances inside the chromatographic column. The target substance flowing out of the chromatographic column is ionized by an ionization source of the mass spectrometry device and then separated and measured by a mass analysis unit according to the mass-to-charge ratio.

[0003] As the ionization source of the mass spectrometry device, for example, an electrospray ionization (ESI) source is used. The ESI source is one of the atmospheric pressure ionization sources that ionize a target substance in an atmospheric pressure atmosphere. The liquid sample is charged using the ESI source, an atomizing gas is blown thereto, and it is sprayed into an ionization chamber. The charged droplets sprayed into the ionization chamber are ionized by the splitting caused by the charge repulsion inside the droplets and the vaporization (desolvation) of the mobile phase.

[0004] In the mass spectrometry device, if substances other than ions derived from the target substance, for example, droplets containing a large amount of neutral molecules derived from the mobile phase, enter the mass analysis unit, the mass analysis unit will be contaminated. Thus, in many ESI sources, the arrangement of the ESI nozzle and the ion introduction unit is determined such that the direction of spraying charged droplets from the ESI nozzle is orthogonal to the direction of introducing ions from the ionization chamber into the mass analysis unit. The ions generated in the ionization chamber are taken into the mass analysis unit along with the air flow generated by the pressure difference between the ionization chamber at atmospheric pressure and the mass analysis unit at vacuum.

[0005] In Patent Document 1, there is a configuration that can improve the ion intake efficiency into the mass analysis unit in the ESI source having the above-described configuration. This ESI source includes: a plate-shaped focusing electrode having an opening that surrounds the ion intake port from the ionization chamber to the mass analysis unit; and a plate-shaped repulsion electrode disposed on the opposite side of the focusing electrode with the jet from the ESI nozzle interposed therebetween. A first voltage having the same polarity as the ion to be measured is applied to the repulsion electrode from a first power supply. In addition, a second voltage having the same polarity as the ion to be measured and having an absolute value smaller than the first voltage is applied to the focusing electrode from a second power supply. Further, the ion intake port is grounded. Ions contained in the jet ejected from the ESI nozzle are pushed toward the focusing electrode by the potential gradient from the repulsion electrode to the focusing electrode and converge toward the ion intake port by the potential gradient from the focusing electrode to the ion intake port near the focusing electrode. On the other hand, neutral molecules are not affected by the potential gradient. Therefore, it is possible to suppress neutral molecules derived from the flow rate and the like from entering the mass analysis unit and contaminating the mass analysis unit, and to improve the ion intake efficiency of the ions derived from the target substance.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: International Publication No. 2018 / 078693 Summary of the Invention

[0009] Technical Problem to be Solved by the Invention

[0010] In a mass analyzer, it is sometimes necessary to continuously perform both positive ion measurement and negative ion measurement. When positive ion measurement and negative ion measurement are continuously performed in the ESI source described in Patent Document 1, the polarities of the voltages applied to the repulsion electrode and the focusing electrode are switched. A first voltage is applied to the repulsion electrode from a first power supply, and a second voltage is applied to the focusing electrode from a second power supply. However, even for a control signal instructing the simultaneous switching of the polarities of the first power supply and the second power supply, the time required for the polarity of the voltage actually output from the first power supply to switch and the time required for the polarity of the voltage output from the second power supply to switch are not necessarily exactly the same. That is, since the response characteristics of the first power supply and the second power supply are not necessarily the same, there is sometimes a deviation between the timing when the polarity switching of the first voltage applied to the repulsion electrode is completed and the timing when the polarity switching of the second voltage applied to the focusing electrode is completed. As a result, an undesirable electric field is formed between the repulsion electrode and the focusing electrode, and the ion intake efficiency into the mass analysis unit deteriorates.

[0011] Here, an ionization source of a mass analyzer has been described as an example. However, in an ion analyzer, the same problem as described above exists in various situations where the behavior of ions is controlled by generating a potential gradient by applying voltages of the same polarity but different magnitudes to two electrodes.

[0012] The technical problem to be solved by the present invention is to provide a technique for suppressing a situation where an undesired electric field is generated between electrodes when switching the polarity of the applied voltage in an ion analyzer that generates a potential gradient by applying voltages of the same polarity but different magnitudes to two electrodes to control the behavior of ions.

[0013] Solution for Solving the Above Technical Problem

[0014] The ion analyzer of the present invention completed to solve the above technical problem includes:

[0015] A power supply circuit in which a power connection part, a first electrode connection part, a first resistance element, a second electrode connection part, a second resistance element, and a ground part are provided in series;

[0016] A power supply connected to the power connection part and outputting a DC voltage of both positive and negative polarities;

[0017] A first voltage supply electrode connected to the first electrode connection part;

[0018] A second voltage supply electrode connected to the second electrode connection part.

[0019] Advantages of the Invention

[0020] In the ion analyzer of the present invention, a power supply circuit in which a power connection part, a first electrode connection part, a first resistance element, a second electrode connection part, a second resistance element, and a ground part are provided in series is used, and a power supply is connected to the power connection part and a voltage of a specified magnitude is applied to the power connection part. Thereby, the specified magnitude of voltage is applied to the first voltage supply electrode connected to the first electrode connection part adjacent to the power connection part. In addition, a voltage corresponding to the specified magnitude of voltage, the resistance value of the first resistance element, and the resistance value of the second resistance element is applied to the second voltage supply electrode connected to the second electrode connection part. That is, in the ion analyzer of the present invention, it is possible to simultaneously output two voltages having a potential difference corresponding to the resistance value of the resistance element to both the first voltage supply electrode and the second voltage supply electrode using a single power supply. Therefore, there is no deviation between the timing when the polarity switching of the first voltage applied to the first voltage supply electrode is completed and the timing when the polarity switching of the second voltage applied to the second voltage supply electrode is completed. Therefore, it is possible to suppress a situation where an undesired electric field is generated between electrodes when switching the polarity of the voltage. Description of the Drawings

[0021] Figure 1 This is a main component diagram of a liquid chromatography mass spectrometry device including an embodiment of the ion analysis device of the present invention.

[0022] Figure 2 This is a diagram for explaining the configuration of the ionization source of the liquid chromatography mass spectrometry device of this embodiment.

[0023] Figure 3 This is a graph showing the voltage changes of the repulsion electrode and the focusing electrode in the ionization source of a conventional mass spectrometry device.

[0024] Figure 4 This is a graph showing the change in the difference between the voltage applied to the repulsion electrode and the voltage applied to the focusing electrode in the ionization source of a conventional mass spectrometry device.

[0025] Figure 5 This is a graph showing the voltage changes of the repulsion electrode and the focusing electrode in this embodiment.

[0026] Figure 6 This is a graph showing the change in the difference between the voltage applied to the repulsion electrode and the voltage applied to the focusing electrode in this embodiment.

[0027] Figure 7 This is a diagram for explaining the configuration of the ion source of a modified example.

[0028] Figure 8 This is a diagram for explaining a modified example of the power supply circuit. Detailed implementation mode

[0029] Regarding the liquid chromatography mass spectrometry device including an embodiment of the ion analysis device of the present invention, the following will be described with reference to the accompanying drawings.

[0030] Figure 1 This is a main component diagram of the liquid chromatography mass spectrometry device of this embodiment. The liquid chromatography mass spectrometry device of this embodiment is generally composed of a liquid chromatograph 1, a mass spectrometer 2, and a control and processing unit 6 that controls their operations.

[0031] The liquid chromatograph 1 includes: a mobile phase container 10 storing a mobile phase, a pump 11 that sucks the mobile phase and conveys it at a constant flow rate, a syringe 12 that injects a specified amount of sample solution into the mobile phase, and a chromatographic column 13 that separates various compounds contained in the sample solution in the time direction. In addition, an autosampler 14 that sequentially introduces a plurality of liquid samples into the syringe 12 is connected to the liquid chromatograph 1.

[0032] The mass analyzer 2 includes an ionization chamber 20, a first intermediate vacuum chamber 30, a second intermediate vacuum chamber 40, and an analysis chamber 50. The ionization chamber 20 has an atmosphere of approximately atmospheric pressure. On the other hand, the analysis chamber 50 is evacuated by a high-performance vacuum pump (not shown) to a high vacuum state of, for example, about 10 -3 ~10 -4 Pa. The first intermediate vacuum chamber 30 and the second intermediate vacuum chamber 40, which are sandwiched between the ionization chamber 20 and the analysis chamber 50, are also evacuated by vacuum pumps (not shown), respectively, so as to form a multi-stage differential exhaust system configuration in which the degree of vacuum gradually increases from the ionization chamber 20 to the analysis chamber 50.

[0033] An ESI ionization probe 21 is disposed in the ionization chamber 20. As Figure 2 shown, the ESI ionization probe 21 has an ESI nozzle 211 and an auxiliary gas nozzle 212. In the ESI nozzle 211, a prescribed high voltage (ESI voltage) is applied to the liquid sample flowing out from the chromatographic column 13 of the liquid chromatograph 1, and an atomizing gas is blown thereto, so as to spray it into the ionization chamber 20 as charged droplets.

[0034] A heating gas is supplied to the auxiliary gas nozzle 212 to promote the vaporization (desolvation) of the mobile phase contained in the liquid sample sprayed from the ESI nozzle 211. The charged droplets sprayed from the ESI ionization probe 21 come into contact with the surrounding atmosphere and are miniaturized. During the process in which the solvent such as the mobile phase evaporates from the droplets, the sample components fly out while being charged and become ions. In front of the spray flow from the ESI ionization probe 21, a ground electrode 22, a repulsion electrode 23, and a focusing electrode 24 are disposed. A prescribed DC voltage is applied to the repulsion electrode 23 and the focusing electrode 24 from the power supply circuit 26.

[0035] The ionization chamber 20 and the first intermediate vacuum chamber 30 communicate with each other through a thin-diameter heated capillary 25. Since there is a pressure difference at both open ends of the heated capillary 25, an air flow flowing from the ionization chamber 20 to the first intermediate vacuum chamber 30 can be formed by this pressure difference. The ions generated in the ionization chamber 20 are sucked into the heated capillary 25 along with the flow of this air flow, and are introduced into the first intermediate vacuum chamber 30 from its outlet end together with the air flow.

[0036] A conical hole body 32 having an opening with a small diameter at the top is provided in the partition wall separating the first intermediate vacuum chamber 30 and the second intermediate vacuum chamber 40. An ion guide 31 composed of a plurality of annular electrodes arranged around the ion optical axis is disposed in the first intermediate vacuum chamber 30. The ions introduced into the first intermediate vacuum chamber 30 are converged near the opening of the conical hole body 32 by the action of the electric field formed by the ion guide 31, and are sent into the second intermediate vacuum chamber 40 through this opening.

[0037] In the second intermediate vacuum chamber 40, a multipole (e.g., octupole) type ion guide 41 composed of a plurality of rod electrodes is provided. By the action of the high-frequency electric field formed by the ion guide 41, ions are converged, and the ions are sent into the analysis chamber 50 through the opening of the conical hole body 42 provided on the partition wall separating the second intermediate vacuum chamber 40 from the analysis chamber 50.

[0038] In the analysis chamber 50, a quadrupole mass filter 51 and an ion detector 52 are arranged. The ions introduced into the analysis chamber 50 are introduced into the quadrupole mass filter 51. By the action of the electric field formed by the high-frequency voltage and the DC voltage applied to the quadrupole mass filter 51, only the ions having a specific mass-to-charge ratio pass through the quadrupole mass filter 51 and reach the ion detector 52. The ion detector 52 generates a detection signal corresponding to the amount of the arrived ions and outputs the detection signal to the control and processing unit 6.

[0039] The control and processing unit 6 includes a storage unit 61 and a measurement control unit 62. The entity of the control and processing unit 6 is a general computer, and the measurement control unit 62 can be specifically implemented as a functional module by a processor executing pre-installed dedicated software. An input unit 7 and a display unit 8 are connected to the control and processing unit 6.

[0040] Regarding the configuration of the ionization chamber 20, refer to Figure 2 for a detailed description. For convenience here, the blowing direction along the central axis of the spray flow from the ESI ionization probe 21 is set as the Z-axis direction, the ion intake direction along the central axis of the heating capillary 25 orthogonal thereto is set as the X-axis direction, and the direction orthogonal to the X-axis direction and the Z-axis direction is set as the Y-axis direction.

[0041] In the ionization chamber 20, a ground electrode 22 is arranged at the position closest to the ESI ionization probe 21. The ground electrode 22 is a flat plate-shaped electrode parallel to the X-Y plane, and an opening 221 centered on the central axis of the spray flow from the ESI ionization probe 21 is formed.

[0042] At the end of the inlet side of the heating capillary 25, a focusing electrode 24 is arranged. The focusing electrode 24 is a flat plate-shaped electrode parallel to the Y-Z plane, and an opening 241 surrounding the end of the inlet side of the heating capillary 25 is formed.

[0043] A flat plate-shaped repulsion electrode 23 parallel to the Y-Z axis plane is arranged opposite to the inlet end of the heating capillary 25 and the focusing electrode 24 across the spray flow. That is, the spray flow from the ESI ionization probe 21 enters the space between the repulsion electrode 23 and the focusing electrode 24 after passing through the opening 221 of the ground electrode 22.

[0044] The ground electrode 22 and the heating capillary 25 are connected to the partition wall of the grounded chamber. Therefore, the potential of these is 0V. On the other hand, a prescribed DC voltage is applied to the repulsion electrode 23 and the focusing electrode 24 from the power supply circuit 26.

[0045] The power supply circuit 26 is a circuit in which a power supply connection portion 261, a first electrode connection portion 262, a first resistance element 263, a second electrode connection portion 264, a second resistance element 265, and a ground portion are provided in series. A power supply P is connected to the power supply connection portion 261. The repulsion electrode 23 is connected to the first electrode connection portion 262. The focusing electrode 24 is connected to the second electrode connection portion 264.

[0046] If a voltage V1 is output from the power supply P, the voltage V1 is applied to the repulsion electrode connected to the first electrode connection portion 262. In addition, a voltage V2 having the same polarity as V1 and having a magnitude corresponding to the resistance value R1 of the first resistance element and the resistance value R2 of the second resistance element is applied to the focusing electrode connected to the second electrode connection portion 264. The absolute value |V1| of the voltage V1 is, for example, in the range of 2 to 5 kV. In addition, the absolute value |V2| of the voltage V2 is, for example, in the range of 1 to 3 kV. Here, |V1| > |V2| > 0.

[0047] In the ESI nozzle 211, a DC high voltage of several kV is applied to the liquid sample. The polarities of the voltage V1 applied to the repulsion electrode 23 and the voltage V2 applied to the focusing electrode 24 are the same as the polarity of the ions to be measured. That is, when the ions to be measured are positive ions, the polarities of the voltages V1 and V2 are both positive. In addition, when the ions to be measured are negative ions, the polarities of the voltages V1 and V2 are both negative.

[0048] Hereinafter, an example of measuring a liquid sample using the liquid chromatography mass spectrometry apparatus of the present embodiment will be described. Here, for the target substance contained in the liquid sample, the case of obtaining a mass spectrum in both the positive ion mode and the negative ion mode will be described. In this example, the resistance value R1 of the first resistance element 263 and the resistance value R2 of the second resistance element 265 are 250 MΩ.

[0049] The user reads a method file in which the measurement conditions of the liquid sample are described from the storage unit 61, and if the measurement start is instructed, the measurement control unit 62 causes each part of the liquid chromatography mass spectrometry apparatus to operate as follows.

[0050] The autosampler 14 injects a preset liquid sample from the syringe 12 into the flow of the mobile phase. The liquid sample to be injected into the mobile phase is introduced into the chromatographic column 13. Inside the chromatographic column 13, the substances contained in the liquid sample are separated from each other and elute. The liquid sample eluting from the chromatographic column 13 of the liquid chromatograph 1 is sequentially introduced into the ESI ionization probe 21. In the ESI ionization probe 21, a high voltage of positive polarity (ESI voltage. For example, several kV) is applied to the liquid sample, thereby spraying positively charged droplets.

[0051] According to the retention time of the target substance, a DC voltage of +4 kV is output from the power supply P in the power supply circuit 26. Thereby, a voltage V1 of +4 kV is applied to the repulsion electrode connected to the first electrode connection portion 262. In addition, a voltage V2 of +2 kV is applied to the focusing electrode connected to the second electrode connection portion 264.

[0052] When the above voltages are applied to the repulsion electrode and the focusing electrode (the ground electrode is grounded), a repulsion electric field having a force that pushes positive ions in the direction from the repulsion electrode 23 to the focusing electrode 24 is formed between the repulsion electrode 23 and the focusing electrode 24. In addition, since the potential difference between the repulsion electrode 23 and the heating capillary 25 is greater than the potential difference between the repulsion electrode 23 and the focusing electrode 24, a reflection electric field having a force that more strongly pushes ions from the repulsion electrode 23 to the heating capillary 25 can be formed. Further, a focusing electric field having a force that pushes positive ions in the direction from the focusing electrode 24 to the heating capillary 25, that is, from the inner edge portion of the opening 241 of the focusing electrode 24 toward its center, is also formed.

[0053] The spray flow containing ions that have passed through the opening 221 of the ground electrode 22 travels downward in the space between the repulsion electrode 23 and the focusing electrode 24. At this time, by the action of the above electric field, the positively charged ions are pushed in the direction of the focusing electrode 24 and separated from the gas flow. In addition, if the ions come near the inlet end of the heating capillary 25, they converge toward the inlet end. On the other hand, neutral molecules such as those derived from the mobile phase contained in the charged droplets travel straight without being affected by the above electric field. Therefore, only the ions can be efficiently introduced into the first intermediate vacuum chamber 30.

[0054] The ions introduced into the first intermediate vacuum chamber 30 are converged by the ion guide 31 and introduced into the second intermediate vacuum chamber 40 through the opening at the top of the cone body 32. The ions introduced into the second intermediate vacuum chamber 40 are further converged by the ion guide 41 and introduced into the analysis chamber 50 through the opening at the top of the cone body 42. The ions introduced into the analysis chamber 50 are mass-separated by the quadrupole mass filter 51 and detected by the ion detector 52. The mass-to-charge ratio passing through the quadrupole mass filter 51 is scanned within a specified range, thereby obtaining mass spectrometry data in the positive ion mode.

[0055] When obtaining mass spectrometry data in the positive ion mode, the measurement control unit 62 reverses the polarity of the voltage applied to each part in the mass analyzer 2. That is, in the ESI ionization probe 21, a high voltage of negative polarity (ESI voltage, for example, several kV) is applied to the liquid sample, thereby spraying negatively charged droplets.

[0056] The output voltage V1 of the power supply P from the power supply circuit 26 is changed to -4 kV. Thereby, a voltage of -4 kV is applied to the repulsion electrode 23, and a voltage of -2 kV is applied to the focusing electrode 24.

[0057] In a conventional mass spectrometry apparatus, power supplies are independently connected to the repulsion electrode 23 and the focusing electrode 24, respectively. For example, a voltage is applied to the repulsion electrode 23 from the first power supply, and a voltage is applied to the focusing electrode 24 from the second power supply. Therefore, even if a control signal for simultaneously switching the polarities of the outputs of the first power supply and the second power supply is given, there is a case where the time required for the polarity of the voltage actually output from the first power supply to switch is not the same as the time required for the polarity of the voltage output from the second power supply to switch.

[0058] That is, in a conventional mass spectrometry apparatus, since the response characteristics of the first power supply and the second power supply are not necessarily the same, a deviation sometimes occurs between the timing when the polarity switching of the first voltage applied to the repulsion electrode is completed and the timing when the polarity switching of the second voltage applied to the focusing electrode is completed. As a result, when switching the polarity of the measurement mode, an undesired electric field is formed between the repulsion electrode 23 and the focusing electrode 24, and the ion introduction efficiency into the mass analysis unit deteriorates.

[0059] Refer to Figure 3 and Figure 4 A specific example is shown. As Figure 3 shown, when the time required for the polarity of the voltage output from the first power supply to switch is shorter than the time required for the polarity of the voltage output from the second power supply to switch, the potential difference formed between the repulsion electrode 23 and the focusing electrode changes as Figure 4 shown. As a result, an overshoot (excessive potential difference) occurs during the polarity switching.

[0060] In contrast, in the present embodiment, since voltages are applied to both the repulsion electrode 23 and the focusing electrode 24 from a single power supply P as Figure 5 shown, the timing when the polarity switching of the voltages applied to the two electrodes is completed is the same as Figure 6 shown. Therefore, it is possible to suppress the occurrence of an undesired electric field between the electrodes when switching the polarity of the voltage.

[0061] Even in conventional mass spectrometers, as long as sufficient time is allowed after performing the positive ion mode, it is possible to perform the negative ion mode on ions derived from the target substance while making the unwanted electric field ineffective. However, in the case of measuring a target substance separated by the chromatographic column of a liquid chromatograph in both the positive ion mode and the negative ion mode, as in the present embodiment, it is necessary to complete the measurements in both modes within the limited time during which the target substance elutes from the chromatographic column. By adopting the configuration of the present embodiment, it is possible to measure ions derived from the target substance in a short time with high sensitivity.

[0062] In the negative ion mode, voltages with polarities reversed from those in the positive ion mode are applied to each part, but the electric potential acting on the ions is the same as in the positive ion mode. That is, between the repulsion electrode 23 and the focusing electrode 24, a repulsion electric field is formed that has a force to push negative ions in the direction from the repulsion electrode 23 toward the focusing electrode 24. In addition, since the potential difference between the repulsion electrode 23 and the heated capillary 25 is larger than the potential difference between the repulsion electrode 23 and the focusing electrode 24, a reflection electric field can be formed that has a force to more strongly push ions from the repulsion electrode 23 toward the heated capillary 25. Further, a focusing electric field is also formed that has a force to push negative ions in the direction from the focusing electrode 24 toward the heated capillary 25, that is, from the inner edge portion of the opening 241 of the focusing electrode 24 toward its center. By the action of these electric fields, negative ions can be efficiently introduced into the inlet end of the heated capillary 25 and then into the first intermediate vacuum chamber 30.

[0063] The ions introduced into the first intermediate vacuum chamber 30 are converged by the ion guide 31 and introduced into the second intermediate vacuum chamber 40 through the opening at the top of the cone-shaped body 32. The ions introduced into the second intermediate vacuum chamber 40 are further converged by the ion guide 41 and introduced into the analysis chamber 50 through the opening at the top of the cone-shaped body 42. The ions introduced into the analysis chamber 50 are mass-separated by the quadrupole mass filter 51 and detected by the ion detector 52. By scanning the mass-to-charge ratio passing through the quadrupole mass filter 51 within a specified range, mass spectrometry data in the negative ion mode can be obtained.

[0064] Next, a modified liquid chromatograph mass spectrometer will be described. Since the configuration of the power supply circuit of the modified liquid chromatograph mass spectrometer is different from that of the above-described embodiment, while the other configurations are the same, the same reference numerals as those in the above-described embodiment are assigned to the components other than the power supply circuit, and the description thereof is omitted.

[0065] Figure 7It is a schematic configuration diagram of an ionization source of a liquid chromatography mass analyzer according to a modified example. The power supply circuit 27 in the modified example is a power supply circuit obtained by adding a first capacitor 271 and a second capacitor 272 to the power supply circuit 26 of the above-described embodiment. The first capacitor 271 is connected in parallel with the first resistor element 263, and the second capacitor 272 is connected in parallel with the second resistor element 265.

[0066] In an atmospheric pressure ionization source such as the ESI source of the above-described embodiment, there is air between the repulsion electrode 23 and the focusing electrode 24. In addition, there is also air between the focusing electrode 24 and the heating capillary 25 or between the ionization chamber 20 and the partition wall of the first intermediate vacuum chamber 30 (hereinafter, these are collectively referred to as GND). Therefore, depending on the configuration (for example, the magnitude of the distance between the electrodes) or the state (the state of contamination of the electrode surface) of each electrode, a non-negligible capacitive load (stray capacitance) may be generated between the repulsion electrode 23 and the focusing electrode 24 or between the focusing electrode 24 and GND. If a stray capacitance is generated between these, there will be a deviation between the timing of applying a voltage to the repulsion electrode 23 and the timing of applying a voltage to the focusing electrode 24, and as a result, the same overshoot as in the past will occur.

[0067] The power supply circuit 27 of the above-described modified example is a power supply circuit used in such a case. The magnitudes of the capacitance C1 of the first capacitor 271 and the capacitance C2 of the second capacitor 272 are determined as follows: The ratio of the capacitance Cpf between the repulsion electrode 23 and the focusing electrode 24 (= C1 + the parasitic capacitance between the repulsion electrode 23 and the focusing electrode 24) to the capacitance Cfg between the focusing electrode 24 and GND (= C2 + the parasitic capacitance between the focusing electrode 24 and GND) is made (almost) the same as the ratio of the resistance value R1 of the first resistor element 263 to the resistance value R2 of the second resistor element 265. However, in practice, it is difficult to measure the magnitudes of the capacitance Cpf between the repulsion electrode 23 and the focusing electrode 24 or the capacitance Cfg between the focusing electrode 24 and GND themselves. Therefore, based on the results of a preliminary measurement in which the capacitance of the first capacitor 271 and / or the second capacitor 272 is appropriately changed to introduce ions of a standard substance and switch the polarity of the measurement target ions, the optimal capacitance of the first capacitor 271 and / or the second capacitor 272 is obtained.

[0068] In addition, the first resistor element 263 and the second resistor element 265 in the power supply circuit 26 of the above-described embodiment and the power supply circuit 27 of the modified example can be set as variable resistors. When the target substance is easily ionizable, ionization is performed near the outlet of the ESI ionization probe 21. When the target substance is difficult to ionize, ionization is performed at a position far from the outlet of the ESI ionization probe 21. That is, depending on the ease of ionization of the substance, the path for introducing ions into the heating capillary 25 is different, and the optimal values of the applied voltages to the repulsion electrode 23 and the focusing electrode 24 are also different. By previously setting the first resistor element 263 and the second resistor element 265 as variable resistors, it is possible to apply the optimal voltage to the repulsion electrode 23 and the focusing electrode 24 for each target substance in a series of measurements, thereby measuring the target substance with high sensitivity.

[0069] In addition, the first capacitor 271 and / or the second capacitor 272 in the power supply circuit 27 of the above-described modified example can be set as variable capacitors. As described above, the magnitude of the capacitive load (stray capacitance) generated between the repulsion electrode 23 and the focusing electrode 24 or between the focusing electrode 24 and the GND may also vary depending on the state of the mass spectrometer (such as the state of contamination on the electrode surface). By setting the first capacitor 271 and / or the second capacitor 272 as variable capacitors, it is possible to set a capacitance suitable for the state of the mass spectrometer at the measurement time point.

[0070] The above-described embodiment and modified example are merely examples, and can be appropriately changed according to the gist of the present invention.

[0071] The above-described embodiment and modified example are both configured as a mass spectrometer, but the same configuration as above can also be used in other ion analyzers such as an ion mobility analyzer.

[0072] In addition, in the above-described embodiment and modified example, the case where a voltage is applied to the repulsion electrode and the focusing electrode disposed in the ionization chamber has been described, but the same power supply circuit as above can also be used for the case where a voltage is applied to other electrodes. As such electrodes, for example, a plurality of ring electrodes constituting the ion guide 31 disposed in the first intermediate vacuum chamber 30 can be cited. As in the case of this ion guide 31, for three or more electrodes, when applying voltages of the same polarity and different magnitudes from each other, as long as Figure 8 shown in the power supply circuit 28, the number of resistor elements and / or capacitor elements can be increased as needed. In addition, as Figure 8 shown, it can also be appropriately configured such that some of the resistor elements are variable resistor elements 281, 282, and some of the capacitor elements are variable capacitor elements 291, 292, etc.

[0073] [Solution]

[0074] Those skilled in the art can understand that the above-mentioned multiple exemplary embodiments are specific examples of the following solutions.

[0075] (Item 1)

[0076] An ion analysis device of one solution includes:

[0077] A power supply circuit, in which a power connection part, a first electrode connection part, a first resistance element, a second electrode connection part, a second resistance element, and a grounding part are arranged in series;

[0078] A power supply, connected to the power connection part and outputting a DC voltage with positive and negative polarities;

[0079] A first voltage supply electrode, connected to the first electrode connection part;

[0080] A second voltage supply electrode, connected to the second electrode connection part.

[0081] In the ion analysis device described in Item 1, a power supply circuit in which a power connection part, a first electrode connection part, a first resistance element, a second electrode connection part, a second resistance element, and a grounding part are arranged in series is used, and a power supply is connected to the power connection part and a voltage of a specified magnitude is applied to the power connection part. Thereby, a voltage of the specified magnitude is applied to the first voltage supply electrode connected to the first electrode connection part adjacent to the power connection part. In addition, a voltage corresponding to the voltage of the specified magnitude, the resistance value of the first resistance element, and the resistance value of the second resistance element is applied to the second voltage supply electrode connected to the second electrode connection part. That is, in the ion analysis device described in Item 1, it is possible to simultaneously output two voltages having a potential difference corresponding to the resistance value of the resistance element to both the first voltage supply electrode and the second voltage supply electrode using a single power supply. Therefore, there is no deviation between the timing when the polarity switching of the first voltage applied to the first voltage supply electrode is completed and the timing when the polarity switching of the second voltage applied to the second voltage supply electrode is completed. Therefore, it is possible to suppress the generation of an undesired electric field between the electrodes when switching the polarity of the voltage.

[0082] (Item 2)

[0083] In the ion analysis device described in Item 1,

[0084] The first voltage supply electrode is a repulsion electrode, and is arranged on the opposite side of the ion inlet that communicates the ionization chamber with the ion analysis part across the ion supply path in the ionization chamber;

[0085] The second voltage supply electrode is a focusing electrode, and has an opening surrounding the ion inlet in the ionization chamber.

[0086] The ion analysis device according to Item 1 can preferably be used as the ion analysis device according to Item 2, wherein a repulsion electrode and a focusing electrode for applying a voltage to form an electric field for transporting ions introduced into the ionization chamber to an ion analysis chamber located at the subsequent stage of the ionization chamber are provided.

[0087] (Item 3)

[0088] In the ion analysis device according to Item 2,

[0089] the ions are generated by an atmospheric pressure ionization source.

[0090] (Item 4)

[0091] In the ion analysis device according to Item 3,

[0092] the atmospheric pressure ionization source is an ESI source.

[0093] By using the ion analysis device according to Item 2 in the ion analysis device having an atmospheric pressure ionization source according to Item 3, particularly in the ion analysis device having an ESI source according to Item 4, the ion intake efficiency can be improved and the measurement sensitivity can be enhanced.

[0094] (Item 5)

[0095] In the ion analysis device according to any one of Items 1 to 4,

[0096] the resistance value of the first resistance element and / or the second resistance element is variable.

[0097] In the ion analysis device according to Item 5, an electric field suitable for the ions of the control object can be formed according to the characteristics of the ions.

[0098] (Item 6)

[0099] In the ion analysis device according to any one of Items 1 to 5,

[0100] In the power supply circuit, a capacitor is connected in parallel with the first resistance element and / or the second resistance element.

[0101] In the ion analysis device according to Item 6, a capacitive load (stray capacitance) that may be generated between the first electrode and the second electrode or between the second electrode and the housing of the analysis device, etc. can be canceled, and an undesirable electric field formed between the first voltage supply electrode and the second voltage supply electrode can be further suppressed.

[0102] (Item 7)

[0103] In the ion analysis device according to Item 6,

[0104] The capacitance of the capacitor is variable.

[0105] In the ion analysis device according to item 7, by appropriately changing the capacitance of the capacitor according to the increase in stray capacitance caused by contamination adhering to the first voltage supply electrode and the second voltage supply electrode, or the change in the state of the position (ionization chamber, etc.) where the two electrodes are arranged, it is possible to further suppress the formation of an undesired electric field between the first voltage supply electrode and the second voltage supply electrode.

[0106] Explanation of reference numerals

[0107] 1 Liquid chromatograph

[0108] 13 Chromatographic column

[0109] 14 Autosampler

[0110] 2 Mass analyzer

[0111] 20 Ionization chamber

[0112] 21 Ionization probe for ESI

[0113] 211 ESI nozzle

[0114] 212 Auxiliary gas nozzle

[0115] 22 Ground electrode

[0116] 221 Opening

[0117] 23 Repulsion electrode (first voltage supply electrode)

[0118] 24 Focusing electrode (second voltage supply electrode)

[0119] 241 Opening

[0120] 25 Heating capillary

[0121] 26, 27, 28 Power supply circuit

[0122] 261 Power supply connection part

[0123] 262 First electrode connection part

[0124] 263 First resistance element

[0125] 264 Second electrode connection part

[0126] 265 Second resistance element

[0127] 271 First capacitor

[0128] 272 Second capacitor

[0129] 281 Variable resistor element

[0130] 291 Variable capacitor

[0131] 30 First intermediate vacuum chamber

[0132] 31 Ion guide

[0133] 40 Second intermediate vacuum chamber

[0134] 41 Ion guide

[0135] 50 Analysis chamber

[0136] 51 Quadrupole mass filter

[0137] 52 Ion detector

[0138] 6 Control and processing unit

[0139] 61 Storage unit

[0140] 62 Measurement control unit

[0141] P Power supply.

Claims

1. An ion analysis device, characterized in that, Comprising: A power supply circuit, which is provided with a power connection part, a first electrode connection part, a first resistance element, a second electrode connection part, a second resistance element and a grounding part connected in series; A power supply, connected to the power connection part and outputting a DC voltage with positive and negative polarities; A first voltage supply electrode, connected to the first electrode connection part; A second voltage supply electrode, connected to the second electrode connection part, The first voltage supply electrode is a repulsion electrode, which is arranged on the opposite side of the ion inlet connecting the ionization chamber and the ion analysis part across the ion supply path in the ionization chamber; The second voltage supply electrode is a focusing electrode, which has an opening surrounding the ion inlet in the ionization chamber.

2. The ion analysis device according to claim 1, characterized in that, The ions are generated by an atmospheric pressure ionization source.

3. The ion analysis device according to claim 2, characterized in that, The atmospheric pressure ionization source is an ESI source.

4. The ion analysis device according to claim 1, characterized in that, The resistance value of the first resistance element and / or the second resistance element is variable.

5. The ion analysis device according to claim 1, characterized in that, In the power supply circuit, a capacitor is connected in parallel with the first resistance element and / or the second resistance element.

6. The ion analysis device according to claim 5, characterized in that, The capacitance of the capacitor is variable.

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