Ion analyzer

Abstract

To provide an ion analyzer capable of preventing a liquid sample from boiling in a sample probe.SOLUTION: A mass spectrometer (ion analyzer) (10) includes an ionization chamber (11), a sample probe (15) fixed on a wall (111) of the ionization chamber (11) that sprays a liquid sample into the ionization chamber (11), a gas heater (20), a fixture (26) for fixing the gas heater (20) to the wall of the ionization chamber (11), and a cooling unit (28) for cooling the fixture (26). The gas heater (20) has a tubular member (21) having both end walls (212) and a peripheral wall (211), a heater (25) for heating the inside of the tubular member (21), a gas inlet (22) and a gas outlet (23) provided on the peripheral wall (211) or end walls (212) of the tubular member (21), and gas outflow tube (24) one end of which is connected to the gas outlet (23), and the other end of which is inserted into the ionization chamber (11).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ion analyzer such as a mass analyzer or an ion mobility analyzer. [Background technology]

[0002] Mass spectrometers used in combination with liquid chromatographs generally have an ionization chamber that ionizes components in a liquid sample eluted from a column of the liquid chromatograph under approximately atmospheric pressure. A nebulizer gas for nebulizing the liquid sample is introduced into the ionization chamber, along with a heating gas heated to a high temperature (e.g., about 400°C) to promote vaporization (desolvation) of the solvent from the nebulized liquid sample.

[0003] Patent Document 1 describes an ion analyzer equipped with a gas heater having a tubular member having both end walls and a peripheral wall, a heater for heating the inside of the tubular member, a gas inlet and a gas outlet provided in the peripheral wall or end wall of the tubular member, and a gas outlet tube (referred to as a "second tubular member" in the document) with one end connected to the gas outlet and the other end inserted into an ionization chamber. In this gas heater, gas is introduced from the gas inlet while the heater heats the inside of the tubular member, and the gas heated inside the tubular member (heating gas) is introduced into the ionization chamber from the gas outlet through the gas outlet tube. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-089227 Summary of the Invention [Problem to be solved by the invention]

[0005] The ion analyzer described in Patent Document 1 requires the introduction of a heating gas at a predetermined position near the liquid sample sprayed into the ionization chamber together with the nebulizer gas. To prevent misalignment between the sprayed liquid sample and the heating gas, both the sample probe that sprays the liquid sample and the gas heater are fixed to the wall of the ionization chamber. In this configuration, the heater heats not only the gas but also the tubular member of the gas heater. The heat from the tubular member is transferred via the wall of the ionization chamber to which it is attached, and the sample probe, which is fixed to the wall, heats up. This causes the liquid sample in the sample probe to boil and spray intermittently into the ionization chamber, resulting in time-varying detection signal intensity regardless of the amount of components contained in the liquid sample.

[0006] Although the above description has been given using a mass spectrometer as an example, similar problems arise in other ion analysis devices, such as ion mobility analyzers, which ionize and analyze a liquid sample.

[0007] An object of the present invention is to provide an ion analyzer that can prevent a liquid sample from boiling in a sample probe. [Means for solving the problem]

[0008] The ion analyzer according to the present invention, which has been made to solve the above problems, is an ionization chamber; a sample probe fixed to a wall of the ionization chamber for spraying a liquid sample into the ionization chamber; a gas heater including a tubular member having both end walls and a peripheral wall, a heater for heating the inside of the tubular member, a gas inlet and a gas outlet provided in the peripheral wall or the end wall of the tubular member, and a gas outlet tube having one end connected to the gas outlet and the other end inserted into the ionization chamber; a fixture for fixing the gas heater to a wall of the ionization chamber; a cooling unit that cools the fixing tool; Equipped with. [Effects of the Invention]

[0009] According to the ion analysis device of the present invention, the fixing device that fixes the gas heater to the wall of the ionization chamber is cooled by a cooling section, thereby preventing heat from the tubular member of the gas heater from being conducted to the sample probe via the fixing device and the wall of the ionization chamber, and preventing the liquid sample from boiling within the sample probe. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a mass spectrometer that is an embodiment of an ion analyzer according to the present invention. [Figure 2] FIG. 2 is a perspective view of a gas heater included in the mass spectrometer of the present embodiment. [Figure 3] FIG. 2 is a cross-sectional view of a gas heater included in the mass spectrometer of the present embodiment. [Figure 4] FIG. 2 is a perspective view of a fixture included in the mass spectrometer of the present embodiment. [Figure 5] FIG. 2 is a partially enlarged perspective view showing a state in which a gas heater is attached to a wall of an ionization chamber in the mass spectrometer of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of an ion analyzer according to the present invention will be described with reference to FIGS.

[0012] (1) Configuration of an embodiment of a mass spectrometer (ion spectrometer) according to the present invention FIG. 1 shows a schematic configuration of a mass spectrometer 10, an ion analyzer according to this embodiment. This mass spectrometer 10 has a multistage differential pumping system including an ionization chamber 11 at approximately atmospheric pressure, a high-vacuum analysis chamber 14 evacuated by a vacuum pump, and a first intermediate vacuum chamber 12 and a second intermediate vacuum chamber 13, which are provided between the ionization chamber 11 and the analysis chamber 14 so that the degree of vacuum is gradually increased. The ionization chamber 11 and the first intermediate vacuum chamber 12 are connected via a thin-diameter capillary 112. The first intermediate vacuum chamber 12 and the second intermediate vacuum chamber 13 are separated by a skimmer 123 with a small hole at their top. The first intermediate vacuum chamber 12 and the second intermediate vacuum chamber 13 are each equipped with an ion guide 121, 131 for focusing ions and transporting them to the subsequent stage. The analysis chamber 14 is equipped with a quadrupole mass filter 141 and an ion detector 142. In this embodiment, the walls (outer walls) of the ionization chamber 11, the first intermediate vacuum chamber 12, the second intermediate vacuum chamber 13 and the analysis chamber 14 are made of aluminum.

[0013] A sample probe (ionization probe) 15 is fixed to the wall 111 of the ionization chamber 11. The sample probe 15 has a metal capillary 151 through which a liquid sample flows, and a nebulizer gas nozzle 152 made of a tubular member provided coaxially outside the capillary 151. The tips of the capillary 151 and the nebulizer gas nozzle 152 are inserted into the ionization chamber 11. A power supply (not shown) that applies a voltage between the capillary 151 and the ground is connected to the capillary 151. A first gas cylinder 153 that supplies nebulizer gas is connected to the nebulizer gas nozzle 152. The nebulizer gas can be, for example, nitrogen gas.

[0014] The mass spectrometer 10 further includes a gas heater 20. The gas heater 20 heats a gas (separate from the nebulizer gas) and supplies it into the ionization chamber 11. Hereinafter, the gas before being heated by the gas heater 20 will be referred to as the "gas before heating," and the gas after the unheated gas has been heated by the gas heater 20 will be referred to as the "heating gas." As shown in FIGS. 2 and 3 , the gas heater 20 in this embodiment includes a cylindrical tubular member 21, two gas inlets 22, a gas outlet 23, a gas outlet pipe 24, and a heater 25.

[0015] The tubular member 21 has a peripheral wall 211 and two end walls 212 that hermetically close both ends of the tubular member 21. Both the peripheral wall 211 and the end walls 212 are made of stainless steel. Two gas inlets 22 are provided in the peripheral wall 211 near both ends of the tubular member 21, one on each side. Gas inlet pipes 221 are connected to the gas inlets 22, respectively, on the outside of the tubular member 21. The gas outlet 23 is provided in the peripheral wall 211 at the center in the longitudinal direction of the tubular member 21. In this embodiment, the circumferential position of the gas outlet 23 is shifted by 70° from the circumferential position of the gas inlet 22.

[0016] One end of the gas outlet pipe 24 is connected to the gas outlet port 23 on the outside of the tubular member 21. The other end of the gas outlet pipe 24 is inserted into the ionization chamber 11 through a hole provided in the wall 111 of the ionization chamber 11.

[0017] The heater 25 is made of nichrome wire and is wound around the outer surface of the peripheral wall of a ceramic bobbin 251 having an outer diameter smaller than the inner diameter of the tubular member 21 to form a coil. A plate 2511 having a width substantially equal to the inner diameter of the bobbin 251 penetrates the interior of the bobbin 251, and both ends of the plate 2511 are fixed to the inner surfaces of the two end walls 212 to hold the plate 2511 within the tubular member 21. Note that FIG. 3 shows a cross section parallel to the axis of the gas inlet pipe 221, and the plate 2511 is shown as a cross section inclined relative to the plate surface. The heater 25 is connected to terminals 252 provided on both end walls 212, and current is supplied through these terminals 252. A thermocouple (not shown in the cross section of FIG. 3) is also provided within the tubular member 21 and is connected to a terminal 253 (FIG. 2) provided outside the tubular member 21.

[0018] The gas heater 20 is fixed to the wall 111 of the ionization chamber 11 by a fixture 26. The fixture 26 is made of a processed stainless steel plate and has a plate-shaped main part 261 that is fixed in contact with the wall 111 of the ionization chamber 11, and a plate-shaped cooled part 262 that is bent 90° from the main part 261 (see FIGS. 2 and 4).

[0019] The main portion 261 is provided with a gas outflow pipe passing hole 263, which is a hole through which the gas outflow pipe 24 passes. If the gas outflow pipe 24 is in contact with the wall 111 of the ionization chamber 11, the heat of the heating gas flowing inside the gas outflow pipe 24 is easily conducted to the wall 111 of the ionization chamber 11. Therefore, in this embodiment, the diameter of the gas outflow pipe passing hole 263 is made larger than the outer diameter of the gas outflow pipe 24 so that the edge of the gas outflow pipe passing hole 263 and the side surface of the gas outflow pipe 24 are not in contact with each other.

[0020] In this embodiment, two cooled portions 262 are provided, separated from each other. Each of the two cooled portions 262 is provided with a gas inlet pipe passing hole 265 through which the gas inlet pipe 221 passes and has a diameter substantially equal to the outer diameter of the gas inlet pipe 221. Furthermore, the gas inlet pipe 221 is provided with a male thread on the outside and a retainer 266 with an inner diameter substantially equal to the outer diameter of the gas inlet pipe 221 and a female thread (note that the gas inlet pipe passing hole 265 is not shown in FIG. 2 because it is hidden by the retainer 266). The retainer 266 is screwed into the gas inlet pipe 221 and pressed against the cooled portion 262. With this structure, the fixing device 26 is cooled by the unheated gas passing through the gas inlet pipe 221 via the edge of the gas inlet pipe passing hole 265 and the retainer 266. Therefore, the gas inlet pipe 221 and the retainer 266 function as the cooling portion 28.

[0021] A second gas cylinder 29 (FIG. 1) that supplies pre-heated gas is connected to the gas inlet pipe 221. The pre-heated gas (and the heating gas obtained by heating it) can be, for example, dry air or nitrogen gas.

[0022] A surface contact portion 27 is provided in a part of the main portion 261 around the gas outflow pipe passing hole 263. The surface contact portion 27 is made of stainless steel that has been polished so that its surface is smoother than that of the main portion 261, and is in surface contact with the outer wall surface of the wall 111 of the ionization chamber 11 around a hole provided in the wall 111 through which the gas outflow pipe 24 passes. The surface contact portion 27 prevents solid or liquid foreign matter from entering the ionization chamber 11 through the gas outflow pipe passing hole 263 and also suppresses gas from flowing in and out between the ionization chamber 11 and the outside through the gas outflow pipe passing hole 263. Note that because the heating gas passing through the gas outflow pipe 24 is heated to approximately 400°C, which heats the gas outflow pipe 24 to a similar temperature, the gas outflow pipe passing hole 263 cannot be airtightly sealed using a sealant with low heat resistance, such as an O-ring. Furthermore, the inside of the ionization chamber 11 is at approximately atmospheric pressure, and some gas is allowed to flow in and out of the chamber, so there is no need to seal it airtight.

[0023] The fixture 26 and the surface contact portion 27 are fixed to the peripheral wall 211 of the tubular member 21 by a common screw 271. The main portion 261 of the fixture 26 is provided with four screw passages 264, which are holes or notches through which screws 267 (see FIG. 5) for fixing the fixture 26 to the wall 111 of the ionization chamber 11 pass. The gas heater 20 is fixed to the wall 111 of the ionization chamber 11 by fixing the tubular member 21 to the fixture 26 using the screws 271 and then fixing the fixture 26 to the wall 111 of the ionization chamber 11 using the screws 267 (FIG. 5). The diameter (in the case of a hole) and width (in the case of a notch) of the screw passages 264 are larger than the diameter of the screws 267, which allows the gas heater 20 to be fixed after fine-tuning the position of the gas outflow tube 24 in the ionization chamber 11. In addition, a recess is provided in the wall 111 of the ionization chamber 11 at a position corresponding to the head of the screw 271, so that the head of the screw 271 does not interfere with the surface contact between the surface contact portion 27 and the wall 111 of the ionization chamber 11.

[0024] The capillary 151 is connected to the outlet of the column 34 of the liquid chromatograph 30 (FIG. 1). In addition to the column 34, the liquid chromatograph 30 is equipped with a mobile phase container 31 in which a mobile phase is stored, a pump 32 that draws in the mobile phase and delivers it at a constant flow rate (or velocity), and an injector 33 that injects a predetermined amount of stock sample solution into the mobile phase. The column 34 separates the components contained in the stock sample solution over time. The liquid sample, which flows out of the column 34 and is made up of the components of the stock sample solution and the mobile phase, is introduced into the capillary 151. The liquid chromatograph 30 is also connected to an autosampler 35 that introduces multiple liquid samples into the injector 33 one by one.

[0025] (2) Operation of the mass spectrometer of this embodiment The mass spectrometer 10 of this embodiment operates in the same manner as a conventional mass spectrometer, except for the gas heater 20 and its peripheral components (fixture 26, cooling unit 28, etc.). Therefore, the following description will focus on the operation of the gas heater 20 and its peripheral components, and only an outline of the operation of the other components of the mass spectrometer 10 will be given.

[0026] In liquid chromatograph 30, a liquid sample in which components contained in the sample stock solution have been separated over time flows out of column 34 as in the conventional case and is introduced into capillary 151 of sample probe 15. In sample probe 15, the liquid sample is released from the tip of capillary 151, and nebulizer gas supplied from first gas cylinder 153 is released from the tip of nebulizer gas nozzle 152, causing a mist of the liquid sample to be sprayed into ionization chamber 11.

[0027] Furthermore, unheated gas at room temperature is supplied from second gas cylinder 29 into tubular member 21 of gas heater 20 through gas inlet pipe 221. In tubular member 21, heat is generated from heater 25 by passing an electric current through heater 25, and the unheated gas is heated. The gas heated to a predetermined temperature (for example, about 400°C) in tubular member 21 is introduced into ionization chamber 11 through gas outlet pipe 24 as heating gas.

[0028] Introduction of the heating gas into the ionization chamber 11 in this manner promotes desolvation of the liquid sample sprayed into the ionization chamber 11 from the sample probe 15. At the same time, ions are generated from the liquid sample by applying a voltage between the capillary 151 and ground. The ions from which the solvent has been desorbed in this manner are focused by the ion guides 121 and 131, pass through the first intermediate vacuum chamber 12 and the second intermediate vacuum chamber 13, and are introduced into the analysis chamber 14. In the analysis chamber 14, a quadrupole mass filter 141 either passes only ions having a specific mass-to-charge ratio or scans the mass-to-charge ratio of the ions that are passed within a predetermined range, and the ions that have passed through the quadrupole mass filter 141 are detected by an ion detector 142.

[0029] In the gas heater 20, as the gas in the tubular member 21 is heated, the tubular member 21 itself is also heated. If heat were conducted from the heated tubular member 21 to the sample probe 15 via the fixture 26 and the wall 111 of the ionization chamber 11, the liquid sample in the sample probe 15 would boil, causing the liquid sample to intermittently eject from the sample probe 15 and resulting in an unstable detection signal. However, in this embodiment, the gas inlet pipe 221 and the presser 266, which form the cooling unit 28, are in thermal contact with the cooled portion 262 of the fixture 26, so the fixture 26 is cooled by the pre-heated gas flowing through the gas inlet pipe 221. This prevents the sample probe 15 from being heated by the heat of the tubular member 21 of the gas heater 20, and thus prevents the liquid sample in the sample probe 15 from boiling. Furthermore, the heat of the fixture 26 is recovered in the pre-heated gas and contributes to heating the pre-heated gas to obtain the heating gas, thereby improving heat utilization efficiency.

[0030] Considering only the need to suppress heat conduction through the fixture 26, it is possible to use a fixture 26 made of a highly insulating material (thermal insulating material). However, because thermal insulating materials are generally more brittle than metals, they are difficult to process into the shape of the fixture 26. Furthermore, over long-term use of the mass spectrometer 10, some of the insulating material may crumble into fine debris, which may enter the ionization chamber 11 through the gap between the gas outlet tube 24 and the hole in the wall 111 of the ionization chamber 11. Furthermore, because thermal insulating materials are generally softer than metals, using a fixture made of a thermal insulating material may cause the position and orientation of the gas outlet tube 24 within the ionization chamber 11 to change over time, which may result in a misalignment of the heating gas introduced into the ionization chamber 11 and the liquid sample, preventing proper desolvation. Therefore, it is preferable to use metal, a hard material that will not crumble even after long-term use, for the fixture 26. Furthermore, because metals generally have good thermal conductivity, it is preferable to cool the metallic fixture 26, as in this embodiment.

[0031] (3) Modifications The present invention is not limited to the above-described embodiment, and various modifications are possible.

[0032] For example, in the above embodiment, the gas inlet pipe 221 and the fixture 26 are brought into thermal contact with each other, and the pre-heated gas flowing in the gas inlet pipe 221 is used as a refrigerant, but instead, a pipe through which a liquid (e.g., water) or gas (e.g., a chlorofluorocarbon alternative) other than the pre-heated gas flows may be brought into thermal contact with the fixture 26. Alternatively, the fixture 26 may be brought into thermal contact with a solid heat bath.

[0033] The shape of the fixture 26 is not limited to that in the above embodiment, and any shape may be used as long as it allows the gas heater 20 to be fixed to the wall 111 of the ionization chamber 11. Furthermore, in the above embodiment, the gas heater 20 is fixed by one fixture 26, but two or more fixtures may be used, and the two or more fixtures may each be cooled by a cooling section.

[0034] The configuration of the gas heater 20 is not limited to that of the above embodiment. For example, in the above embodiment, the gas inlet 22 and the gas outlet 23 are arranged circumferentially offset by 70° around the tubular member 21, but they may be arranged circumferentially offset by 180° or another angle. The positions of the gas inlet 22 and the gas outlet 23 in the longitudinal direction of the tubular member 21 are also not limited to those of the above embodiment. In addition, the gas inlet 22 and / or the gas outlet 23 may be provided in the end wall 212 of the tubular member 21. The number of gas inlets 22 is not limited to two as in the above embodiment, but may be one, three, or more. Furthermore, although the heater 25 is provided in the internal space of the tubular member 21 in the above embodiment, it may be provided within the wall of the tubular member 21 or on the outside of the tubular member 21. In addition, the heater 25 is not limited to being made of nichrome wire as in the above embodiment, and any heater capable of heating the internal space of the tubular member 21 can be used. The material of the tubular member 21 is not limited to stainless steel in the above embodiment, and any material can be used as long as it is resistant to the temperature of the gas inside the tubular member 21. However, similar to the fixing device 26, it is preferable to use a metal material for the tubular member 21 that will not crumble over long periods of use.

[0035] Furthermore, the configurations of the mass spectrometer and the liquid chromatograph are not limited to those described in the above embodiments and can be modified as appropriate. Alternatively, the present invention can be applied to a mass spectrometer that is not used in conjunction with a liquid chromatograph. Furthermore, the present invention can be applied to ion analysis devices other than mass spectrometers, such as ion mobility analyzers.

[0036] [Aspect] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0037] (Section 1) The ion analyzer according to paragraph 1 is an ionization chamber; a sample probe fixed to a wall of the ionization chamber for spraying a liquid sample into the ionization chamber; a gas heater including a tubular member having both end walls and a peripheral wall, a heater for heating the inside of the tubular member, a gas inlet and a gas outlet provided in the peripheral wall or the end wall of the tubular member, and a gas outlet tube having one end connected to the gas outlet and the other end inserted into the ionization chamber; a fixture for fixing the gas heater to a wall of the ionization chamber; a cooling unit that cools the fixing tool; Equipped with.

[0038] According to the ion analysis device of paragraph 1, the fixing device that fixes the gas heater to the wall of the ionization chamber is cooled by the cooling unit, so that the heat from the tubular member of the gas heater is prevented from being conducted to the sample probe via the fixing device and the wall of the ionization chamber, and the liquid sample can be prevented from boiling within the sample probe.

[0039] (Section 2) The ion analysis device according to the second aspect is the ion analysis device according to the first aspect, wherein the cooling unit has a gas inlet pipe having one end connected to the gas inlet, and the fixing device is in thermal contact with the gas inlet pipe.

[0040] In the ion analyzer according to the second aspect, the fixing device is in thermal contact with the gas inlet pipe, so the fixing device is cooled by the pre-heating gas flowing through the gas inlet pipe. In addition, the heat of the fixing device is recovered in the pre-heating gas, which contributes to heating the pre-heating gas to obtain the heating gas, thereby improving the efficiency of heat utilization.

[0041] (Section 3) The ion analyzer according to paragraph 3 is the ion analyzer according to paragraph 1 or 2, wherein the fixing device is made of metal.

[0042] According to the ion analyzer of paragraph 3, because the fixture is made of metal, it will not crumble over long periods of use, generating dross, and such dross will not get in and contaminate the inside of the ionization chamber. In addition, because a metal fixture is difficult to deform, the position of the gas outlet tube in the ionization chamber is unlikely to shift, making it possible to prevent misalignment of the positional relationship between the liquid sample sprayed from the sample probe and the heating gas supplied from the gas outlet tube.

[0043] (Section 4) The ion analyzer according to item 4 is the ion analyzer according to any one of items 1 to 3, wherein the fixture has a gas outflow pipe passage hole through which the gas outflow pipe passes and which has a diameter larger than the outer diameter of the gas outflow pipe.

[0044] According to the ion analyzer of paragraph 4, the diameter of the gas outlet pipe passage hole is larger than the outer diameter of the gas outlet pipe, so the gas heater can be attached to the wall of the ionization chamber with a fixture without the side of the gas outlet pipe coming into contact with the edge of the gas outlet pipe passage hole, thereby preventing heat from being transferred from the gas outlet pipe to the fixture. [Explanation of symbols]

[0045] 10...Mass spectrometer 11...Ionization chamber 111...wall 112...Capillary 12...First intermediate vacuum chamber 121, 131...Ion Guide 123...Skimmer 13...Second intermediate vacuum chamber 14…Analysis room 141...Quadrupole mass filter 142...Ion detector 15...Sample probe 151...Capillary 152...Nebulizer gas nozzle 153...First gas cylinder 20...Gas heater 21...Tubular member 211...Circumferential wall of tubular member 212...End wall of tubular member 22...Gas inlet 221...Gas inlet pipe 23...Gas outlet 24...Gas outflow pipe 25...Heater 251...Bobbin 2511...Bobbin fixing plate 252...Heater terminal 253...Thermocouple terminal 26…Fixing tool 261...Main part of fixing device 262...Cooled part of fixture 263...Gas outflow pipe passage hole 264...Screw passage 265...Gas inlet pipe passage hole 266... ​​Clamp 267, 271...Screws 27...surface contact part 28...Cooling section 29...Second gas cylinder 30...Liquid chromatograph 31...Mobile phase container 32...Pump 33...Injector 34...Column 35...Autosampler

Claims

1. an ionization chamber; a sample probe fixed to a wall of the ionization chamber for spraying a liquid sample into the ionization chamber; a gas heater including a tubular member having both end walls and a peripheral wall, a heater for heating the inside of the tubular member, a gas inlet and a gas outlet provided in the peripheral wall or the end wall of the tubular member, and a gas outlet tube having one end connected to the gas outlet and the other end inserted into the ionization chamber; a fixture for fixing the gas heater to a wall of the ionization chamber; a cooling unit that cools the fixing tool; An ion analyzer comprising:

2. 2. The ion analyzer according to claim 1, wherein the cooling unit has a gas inlet pipe having one end connected to the gas inlet, and the fixture is in thermal contact with the gas inlet pipe.

3. The ion analyzer according to claim 1 or 2, wherein the fixture is made of metal.

4. 4. The ion analyzer according to claim 1, wherein the fixture has a gas outflow pipe passage hole through which the gas outflow pipe passes and which has a diameter larger than the outer diameter of the gas outflow pipe.

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