Ionization device, mass spectrometry system, and ionization method

Abstract

The ionization device has: an ion formation unit that ionizes an analyte by corona discharge, and a transfer unit that transfers the ionized analyte to a mass spectrometry device. The ion formation unit and the transfer unit are separated by one of a pair of electrodes that generate corona discharge and that has an opening.

Description

Technical Field

[0001] The present invention relates to an ionization device, a mass spectrometry system, and an ionization method. Background Art

[0002] Non-Patent Document 1 discloses an ion source for ionizing a substance to be analyzed by a mass spectrometry device. This ion source combines a piston with excellent heat resistance and a solenoid pulse valve, and performs corona discharge using a discharge needle disposed in an open space of an ion source unit, thereby ionizing the substance and transferring it to the mass spectrometry device.

[0003] Prior Art Documents

[0004] Non-Patent Documents

[0005] Non-Patent Document 1: Kenzo Hiraoka, "Gas Phase Ionization Method Using Penning Ionization as a Source", J.Mass Spectrom.Soc.Jpm.Vol.65, No.3, 2017 P107 - P112 [Retrieved on November 29, Reiwa 1] Internet <URL:https: / / www.jstage.jst.go.jp / article / massspec / 65 / 3 / 65_S17-08 / _pdf> Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] However, in the prior art shown in Non-Patent Document 1, Figure 34 as shown, since corona discharge is performed in the open space of the ion source unit, the ionized substance diffuses into the open space, and the analysis sensitivity of the ionized substance sometimes decreases.

[0008] The present disclosure has been made in view of the above circumstances, and an object thereof is to obtain an ionization device that improves the analysis sensitivity of an ionized substance.

[0009] Means for Solving the Problems

[0010] The ionization device according to the present disclosure includes: an ion formation unit that ionizes a substance to be analyzed by corona discharge, and a transfer unit that transfers the ionized substance to be analyzed to a mass spectrometry device, and the ion formation unit and the transfer unit are separated by one of a pair of electrodes that generate the corona discharge and has an opening.

[0011] Advantages of the Invention

[0012] According to the present disclosure, it is possible to improve the analysis sensitivity of an ionized substance. Brief Description of the Drawings

[0013] Figure 1 A diagram showing a schematic configuration of the ionization device 300 according to this embodiment.

[0014] Figure 2 To show Figure 1 A diagram showing the state in which the substance ionized by corona discharge is transferred to the mass spectrometry device 200 in the ionization device shown.

[0015] Figure 3 A diagram showing the overall configuration of the mass spectrometry system 100 including the ionization device 300.

[0016] Figure 4 A perspective view of the housing 8 of the mass spectrometry device 200 and the ionization device 300.

[0017] Figure 5 Viewed from the back side Figure 4 A diagram of the housing 8 shown.

[0018] Figure 6 A diagram showing the housing 8 that is openably and closably mounted on the mass spectrometry device 200 through a hinge structure, and the ion inlet 201 provided in the mass spectrometry device 200.

[0019] Figure 7 A perspective view of the ionization device 300 provided in the housing 8.

[0020] Figure 8 An exploded perspective view of the housing 8 and the ionization device 300.

[0021] Figure 9 A perspective view of the insulating plate 1.

[0022] Figure 10 A side view of the insulating plate 1 viewed from the positive Y-axis direction.

[0023] Figure 11 A side view of the insulating plate 1 viewed from the negative X-axis direction.

[0024] Figure 12 A perspective view of the discharge plate 4.

[0025] Figure 13 A side of the discharge plate 4 viewed from the negative X-axis direction.

[0026] Figure 14 A perspective view of the insulating plate 2.

[0027] Figure 15 A side view of the insulating plate 2 viewed from the negative Y-axis direction.

[0028] Figure 16 A perspective view of the discharge plate 5.

[0029] Figure 17 The side view of the discharge plate 5 as observed from the positive Y-axis direction.

[0030] Figure 18 The perspective view of the discharge electrode 6.

[0031] Figure 19 The side view of the discharge electrode 6 as observed from the Y-axis direction.

[0032] Figure 20 The perspective view of the insulating plate 3.

[0033] Figure 21 The side view of the insulating plate 3 as observed from the positive X-axis direction.

[0034] Figure 22 Is Figure 7 The sectional view on the XZ plane of the ionization device 300 and the housing 8 shown in the figure.

[0035] Figure 23 The flowchart for explaining the method of ionizing a substance using the mass spectrometry device 200.

[0036] Figure 24 The graph showing the change in ion detection intensity with respect to the distance between electrodes in a state where the discharge voltage is set to 2.0 kV.

[0037] Figure 25 The graph showing the change in ion detection intensity with respect to the distance between electrodes in a state where the discharge voltage is set to 2.5 kV.

[0038] Figure 26 The graph showing the change in ion detection intensity with respect to the distance between electrodes in a state where the discharge voltage is set to 3.0 kV.

[0039] Figure 27 The graph showing the change in ion detection intensity with respect to the distance between electrodes using the ionization device 300 according to the present embodiment.

[0040] Figure 28 The graph showing the change in ion detection intensity with respect to the distance between electrodes using the prior art.

[0041] Figure 29 The graph for charting the mass distribution of ions generated using the ionization device 300 according to the present embodiment.

[0042] Figure 30 The graph for charting the mass distribution of ions generated using the prior art.

[0043] Figure 31A diagram showing the measurement results when volatile substances generated from a sample (e.g., beer) are ionized using the ionization device 300 according to this embodiment.

[0044] Figure 32 A diagram showing the measurement results when volatile substances generated from a sample (e.g., beer) are ionized using the prior art.

[0045] Figure 33 A diagram showing the correspondence between the discharge voltage and the distance between electrodes set when ionized using the ionization device 300 according to this embodiment.

[0046] Figure 34 A diagram showing an example of an ionization device of the prior art. Detailed Embodiment

[0047] Hereinafter, the detailed embodiment will be described with reference to the drawings. In the following description, for parts common to the respective drawings, the same reference numerals may be attached and the description may be omitted. In addition, for ease of understanding, the scales of the respective components in the respective drawings may sometimes be different from the actual ones. Additionally, the X-axis direction, Y-axis direction, and Z-axis direction respectively represent the direction parallel to the X-axis, the direction parallel to the Y-axis, and the direction parallel to the Z-axis. The X-axis direction, Y-axis direction, and Z-axis direction are orthogonal to each other. In the X-axis direction, the direction indicated by the arrow is set as the positive X-axis direction, and the direction opposite to this direction is set as the negative X-axis direction. In the Y-axis direction, the direction indicated by the arrow is set as the positive Y-axis direction, and the direction opposite to this direction is set as the negative Y-axis direction. In the Z-axis direction, the direction indicated by the arrow is set as the positive Z-axis direction, and the direction opposite to this direction is set as the negative Z-axis direction. The X-axis direction is the horizontal width direction when the ionization device is viewed from the front. The Y-axis direction is the height direction of the ionization device. The Z-axis direction is the depth direction of the ionization device.

[0048] Figure 1 A diagram showing the outline of the ionization device 300 according to this embodiment. Figure 2 A diagram showing the state where the substances ionized by corona discharge are transferred to the mass spectrometry device 200.

[0049] Figure 1 、 2 In 2 , 30 is an ion formation part, and in the ion formation part (space), an electrode 6 and an electrode 4 that generate corona discharge are provided. The discharge electrode 4 has an opening 4a and is arranged so as to generate corona discharge between the electrode 6 and the end (edge) of the opening 4a of the electrode 4. Inside the hole of the opening 4a of the electrode 4, a transfer part for transferring the substance to be ionized to the mass spectrometry device 200 is formed. In addition, the transfer part can be constituted by the opening 4a of the electrode and the through hole (1b) of the insulating plate 1 described later. 201 is the ion inlet of the mass spectrometry device 200.

[0050] The ionized analyte (33a) is taken into the analysis device through an attracting device (not shown) provided in the mass spectrometry device 200 from the ion introduction port 201.

[0051] The elliptical portion indicated by reference numeral 31 represents the corona discharge generated in the region where the discharge electrode 6 faces the discharge plate 4. 33 represents the generated corona discharge. The substance to be measured 32 is supplied to the vicinity of the corona discharge through the tube 12. 700 is the power source for generating the corona discharge.

[0052] In addition, in the present embodiment, the ionization device is provided with an electrode for generating a corona discharge. Figure 34 As shown, no corona discharge occurs between a part of the mass spectrometry device, so the mass spectrometry device is not directly and strongly affected by the corona discharge. Therefore, the mass spectrometry device is not severely damaged related to failures or malfunctions due to the corona discharge.

[0053] Furthermore, the opening 4a of the discharge electrode 4 and the ion introduction port of the mass spectrometry device 200 can be substantially arranged on a straight line. In addition, the distance between the ion transfer section and the ion introduction port of the mass spectrometry device can be shortened. Therefore, the ionized substance can be transferred to the mass spectrometry device without diffusing into the open space, thereby improving the analysis sensitivity of the ionized substance.

[0054] Figure 3 FIG. is a diagram showing the overall configuration of a mass spectrometry system 100 including the ionization device 300 according to the present embodiment. The mass spectrometry system 100 includes: a mass spectrometry device 200, an ionization device 300, a housing 8 for fixing the ionization device 300 to the mass spectrometry device 200, a gas attracting device 400 such as a vacuum pump connected to the ionization device 300, and a DC power supply 700. The DC power supply 700 can be, for example, a power supply unit mounted on the mass spectrometry device 200 or a power supply unit different from the power supply unit (a power supply unit independent of the mass spectrometry device 200).

[0055] Figure 4 FIG. is a perspective view of the housing 8 of the mass spectrometry device 200 and the ionization device 300. The housing 8 is arranged on the front surface of the mass spectrometry device 200. The front surface of the mass spectrometry device 200 is equal to the end surface of the mass spectrometry device 200 in the negative Z-axis direction. The housing 8 is arranged on the front surface of the mass spectrometry device 200 through, for example, a hinge structure. In addition, the mounting structure of the housing 8 to the mass spectrometry device 200 is not limited to the hinge structure and can be, for example, screw tightening. The housing 8 is provided with a pressing block 9. The pressing block 9 is screwed to the housing 8, for example, at a position near the end in the positive X-axis direction within the end surface of the housing 8 in the negative Z-axis direction.

[0056] Figure 5 For the general Figure 4 The frame 8 shown is viewed from the back side. A pipe 500 connected to the gas suction device 400 is connected to the end face side of the frame 8 in the negative Y-axis direction. The pipe 500 is connected to the recessed portion 8a formed on the back side of the frame 8. The back side of the frame 8 is equal to the end face of the frame 8 in the positive Z-axis direction. The ionization device 300 is screwed to the center of the bottom 8a1 of the recessed portion 8a. The ionization device 300 is formed with a through hole 1b connected to the recessed portion 8a of the frame 8. An O-ring 14 is provided in a manner to surround the recessed portion 8a of the frame 8.

[0057] Figure 6 The figure shows a housing 8 which is attached to the mass spectrometer 200 so as to be openable and closable by a hinge structure, and an ion intake port 201 provided in the mass spectrometer 200 . Figure 6 As shown in FIG. 1 , the front end of the ion intake port 201 is provided on the front of the mass spectrometer 200. The frame 8 is covered in a manner to cover the ion intake port 201. If the above-mentioned pressing block 9 is hung with a stopper 21, the frame 8 is fixed to the mass spectrometer 200 (see FIG. 1 ) in a state where the front end of the ion intake port 201 faces the through hole 1b of the ionization device 300. Figure 4 ).at this time, Figure 6 The O-ring 14 shown is in close contact with the front surface of the mass spectrometer 200 , thereby forming a sealed space between the recessed portion 8 a of the frame 8 and the mass spectrometer 200 .

[0058] Next, refer to Figures 7 to 22 , the structure of the frame 8 and the ionization device 300 will be described in detail.

[0059] Figure 7 It is a perspective view of the ionization device 300 provided in the housing 8 . Figure 7 The figure shows a state where a plurality of components constituting the housing 8 are assembled in the ionization device 300 . Figure 8 FIG. 8 is an exploded perspective view of the frame 8 and the ionization device 300. Figure 8 As shown, the ionization device 300 includes an insulating plate 1 , a discharge plate 4 , an insulating plate 2 , a discharge plate 5 , a discharge electrode 6 , an insulating plate 3 , a spacer plate 7 , and a tube 12 .

[0060] The insulating plate 2 is a first insulating portion. The discharge electrode 6 is a first electrode provided on the insulating plate 2. The insulating plate 1 is a second insulating portion provided between the insulating plate 2 and the mass spectrometer 200. The discharge plate 4 is a second electrode provided on the insulating plate 1 at a certain distance (e.g., 1.5 mm) from the discharge electrode 6 and grounded.

[0061] Figure 9 It is a three-dimensional view of the insulating plate 1. Figure 10It is a side view of the insulating plate 1 as viewed from the positive Y-axis direction. Figure 11 It is a side view of the insulating plate 1 as viewed from the negative X-axis direction.

[0062] The insulating plate 1 is an insulating member that can be inserted into the concave portion 8b of the frame 8. The material of the insulating plate 1 is, for example, PTFE (polytetrafluoroethylene). In addition, the material of the insulating plate 1 is not limited to PTFE. For example, it can be a fluorine-based adhesive such as PVDF (poly(1,1-difluoroethylene)), EPBR (ethylene-propylene-butadiene rubber), SBR (styrene-butadiene rubber), CMC (isoprene rubber, carboxymethyl cellulose), etc., and can be an insulating resin of the PP (polypropylene) series or nylon series. They can be used alone or in combination of two or more.

[0063] A concave portion 1a, a through hole 1b, a screw hole 1c, a convex portion 1d, and a plurality of screw holes 1e are formed on the insulating plate 1.

[0064] The concave portion 1a is a concave pit formed on the end face of the insulating plate 1 in the negative Z-axis direction. The discharge plate 4 shown in Figure 8 is inserted into the concave portion 1a.

[0065] The through hole 1b has a function of transferring the ionized substance to the mass spectrometry device 200. The ionized substance is a substance ionized in the space including the region where the discharge electrode 6 and the discharge plate 4 face each other by the corona discharge generated between the discharge electrode 6 and the discharge plate 4. The details of the space including the region where the discharge electrode 6 and the discharge plate 4 face each other will be described later.

[0066] The screw hole 1c is a hole into which a connecting member (such as the screw 15 shown in Figure 8 ) for fixing the discharge plate 4 to the insulating plate 1 is inserted.

[0067] The convex portion 1d is formed on the end face of the insulating plate 1 in the positive Z-axis direction and is formed to be able to be inserted into the opening portion 8a2 of the frame 8 without a gap.

[0068] The screw hole 1e is a hole into which a plurality of connecting members (such as the screw 15 shown in Figure 8 ) for fixing the insulating plate 1 to the frame 8 are inserted.

[0069] When the frame 8 fixes the insulating plate 1, the convex portion 1d of the insulating plate 1 is inserted into the opening portion 8a2, and the insulating plate 1 is inserted into the concave portion 8b of the frame 8. Then, a plurality of screws 15 are screwed into the screw holes 1e of the insulating plate 1 through the bottom portion 8a1 of the frame 8, so that the insulating plate 1 is fixed to the frame 8.

[0070] Figure 12 It is a perspective view of the discharge plate 4. Figure 13FIG. 0 is a side view of the discharge plate 4 as viewed from the negative X-axis direction. The discharge plate 4 is a conductive member that is embedded in the recess 1a of the insulating plate 1 and is connected to, for example, Figure 3 the negative electrode of the DC power supply 700 shown. The material of the discharge plate 4 is, for example, SUS304, which is an austenitic stainless steel alloy. In addition, the material of the discharge plate 4 is not limited to SUS304, and it can be SUS303, a ferritic stainless steel alloy, a titanium-based alloy, an aluminum alloy, a copper alloy, cast iron, steel, an iron alloy, etc. As the ferritic stainless steel alloy, it is SUS430, etc. As the aluminum alloy, it is A6063, A5056, etc. As the copper alloy, it is chromium copper, beryllium copper, etc. As the cast iron, it is gray cast iron represented by FC200, nodular graphite cast iron represented by FCD400, etc. As the steel, it is carbon steel represented by SC450, carbon steel pipe for mechanical structures represented by STKM, etc. As the iron alloy, it is chromium molybdenum steel represented by SCM, etc.

[0071] In addition, the discharge plate 4 can be a conductive material or a non-conductive material, and a conductive plating can be applied to the surface of the discharge plate 4. As the plating material, it can be, for example, carbon, titanium coating, or a material in which a conductive material is mixed in a non-conductive material.

[0072] The discharge plate 4 is formed with a screw hole 4b, a screw hole 4c, and a through hole 4a.

[0073] The above-mentioned screw 15 is inserted into the screw hole 4b. Thus, the discharge plate 4 is fixed to the insulating plate 1.

[0074] In the screw hole 4c, a screw for fixing a conductive terminal provided at the front end of a wiring 600 that is connected to, for example, Figure 3 the negative electrode of the DC power supply 700 shown is inserted. By screwing this screw into the screw hole 4c of the discharge plate 4, the negative electrode of the DC power supply 700 is electrically connected to the discharge plate 4.

[0075] The through hole 4a is a hole that penetrates the discharge plate 4 in the Z-axis direction and has a function of transferring the ionized substance to the mass spectrometry device 200. In addition, the first thickness t1 in the Z-axis direction of the portion of the discharge plate 4 where the through hole 4a is formed is thinner than the second thickness t2 in the Z-axis direction of the portion of the discharge plate 4 where the screw hole 4b is formed. The first thickness t1 is, for example, 0.8 to 1.2 mm, and the second thickness t2 is, for example, 5.0 to 7.0 mm. By configuring the discharge plate 4 in this way, when the discharge plate 4 is embedded in the recess 1a of the insulating plate 1, it is possible to arrange it close to the tip of the discharge needle of the discharge electrode 6 in the through hole 4a of the discharge plate 4, and it is possible to provide a space including the region where the discharge electrode 6 and the discharge plate 4 face each other.

[0076] The corner portion 4e of the through hole 4a functions as a discharge electrode of the discharge plate 4. The corner portion 4e is a portion where the end face 4d of the discharge plate 4 in the negative Z-axis direction intersects with the wall surface 4a1 forming the through hole 4a.

[0077] Figure 14 It is a perspective view of the insulating plate 2. Figure 15 It is a side view of the insulating plate 2 observed from the negative Y-axis direction. The insulating plate 2 is an insulating member fixed to the end face of the insulating plate 1 in the negative Z-axis direction in a manner of sandwiching the discharge plate 4. The material of the insulating plate 2 is, for example, PTFE. In addition, the material of the insulating plate 2 is not limited to PTFE. For example, it can be a fluorine-based adhesive such as PVDF, EPBR, SBR, CMC, etc. They can be used alone or in combination of two or more.

[0078] The insulating plate 2 is formed with a recess 2a, a through hole 2b, screw holes 2c, screw holes 2f, screw holes 2h, and a through hole 2i.

[0079] The recess 2a is a pit formed on the end face 2d of the insulating plate 2 in the negative Z-axis direction that can accommodate the discharge plate 5 and the discharge electrode 6. A through hole 2i that penetrates from the bottom face of the recess 2a to the end face 2g of the insulating plate 2 in the positive Z-axis direction is formed on the bottom face in the positive Z-axis direction of the bottom face of the recess 2a. The through hole 2i is a hole for inserting the discharge needle of the discharge electrode 6.

[0080] Two screw holes 2c are formed on the end face 2d of the insulating plate 2 in the negative Z-axis direction. The two screw holes 2c are arranged separately along the Y-axis direction in a manner of sandwiching the recess 2a.

[0081] A through hole 2b for inserting the tube 12 is formed from the inclined face 2e of the insulating plate 2 toward the end face 2g of the insulating plate 2 in the positive Z-axis direction.

[0082] The tube 12 is a cylindrical member made of, for example, ceramic, and is a pipe for introducing a substance to be analyzed into a mass spectrometry device 200 into a space in a region where the discharge electrode 6 faces the discharge plate 4. The tube 12 is inserted into the through hole 2b of the insulating plate 2 via a backing plate 7 screwed to the inclined face 2e of the insulating plate 2.

[0083] The backing plate 7 is screwed to the inclined face 2e of the insulating plate 2 by screwing Figure 8 the screw 20 shown into the screw hole 2f on the inclined face 2e of the insulating plate 2. The inclination angle θ ( Figure 15 ) of the inclined face 2e with respect to the face parallel to the end face 2d is preferably 25 to 35°, for example, 30°.

[0084] In addition, it is preferable to provide Figure 8The O-ring 13 shown. By providing the O-ring 13, the airtightness between the through-hole 2b of the insulating plate 2 and the tube 12 is increased.

[0085] The screw hole 2h is a hole into which a connecting member (such as Figure 8 the screw 15 shown) for fixing the insulating plate 2 to the insulating plate 2 is screwed.

[0086] Figure 16 is a perspective view of the discharge plate 5. Figure 17 is a side view of the discharge plate 5 as viewed from the positive Y-axis direction. The discharge plate 5 is a conductive member that is inserted into the recess 2a of the insulating plate 2 and is formed in a size capable of holding the discharge needle of the discharge electrode 6. The material of the discharge plate 5 is, for example, SUS304. In addition, the material of the discharge plate 5 is not limited to SUS304, and may be SUS303, SUS430, etc., and may be the above-mentioned aluminum alloy, copper alloy, cast iron, steel, ferroalloy, etc.

[0087] The discharge plate 5 is formed with a through-hole 5a, a screw hole 5b, and a screw hole 5c.

[0088] The through-hole 5a is a hole that penetrates the discharge plate 5 in the Z-axis direction so that the discharge needle of the discharge electrode 6 can be inserted.

[0089] In the screw hole 5b, a screw for fixing a conductive terminal provided at the front end of a wiring 600 connected to the positive electrode of, for example, Figure 3 the DC power supply 700 shown is inserted. By screwing this screw into the screw hole 5b of the discharge plate 5, the positive electrode of the DC power supply 700 is electrically connected to the discharge plate 5. The screw hole 5c is a hole for inserting a screw for fixing the discharge plate 5 to the insulating plate 2.

[0090] Figure 18 is a perspective view of the discharge electrode 6. Figure 19 is a side view of the discharge electrode 6 as viewed from the Y-axis direction. The material of the discharge electrode 6 is, for example, SUS430. In addition, the material of the discharge electrode 6 is not limited to SUS430, and may be SUS303, SUS304, etc., and may be the above-mentioned aluminum alloy, copper alloy, cast iron, steel, ferroalloy, etc.

[0091] The discharge electrode 6 includes a pedestal 6a and a discharge needle 6b.

[0092] The pedestal 6a is a cylindrical member having a flat end face 6d formed in a manner that forms a contact surface with the insulating plate 3. A discharge needle 6b is provided at the end face of the pedestal 6a on the side opposite to the end face 6d side. The discharge needle 6b extends from the pedestal 6a toward the positive Z-axis direction, and its front end portion 6c is arranged so as to face the through hole 4a of the discharge plate 4. The region of the discharge needle 6b near the front end portion 6c has a shape with a thin front end, and the inclination angle θ of this region with the front end portion 6c as the vertex is preferably 15 to 25°, for example, 20°.

[0093] Figure 20 is a perspective view of the insulating plate 3. Figure 21 is a side view of the insulating plate 3 observed from the positive X-axis direction. The material of the insulating plate 3 is, for example, PTFE. In addition, the material of the insulating plate 3 is not limited to PTFE. For example, it can be a fluorine-based adhesive such as PVDF, EPBR, SBR, CMC, etc. They can be used alone as one kind, or two or more kinds can be used in combination.

[0094] The insulating plate 3 is formed with two through holes 3a penetrating the insulating plate 3 along the Z-axis direction. The end face 3b of the insulating plate 3 in the positive Z-axis direction is connected to the pedestal 6a of the discharge electrode 6, and the screws 16 as shown are inserted into the two through holes 3a, and these screws 16 are screwed into the insulating plate 2, so that the insulating plate 3 is fixed to the insulating plate 2. Figure 8 as shown, and the insulating plate 3 is fixed to the insulating plate 2.

[0095] Return to Figure 8 , the frame 8 includes a pressure block 9, a pressure block 10, and a positioning pin 11. From the viewpoint of preventing the leakage of electromagnetic waves generated by corona discharge, the material of the frame 8 is preferably, for example, a metal such as aluminum (alloy) or stainless steel. In addition, in order to easily confirm the transfer state of the ionized substance to the mass spectrometry device 200, PMMA (polymethyl methacrylate resin) having high transparency can be used. When using such a resin with high transparency, from the viewpoint of preventing electromagnetic wave leakage, it is preferable to form a transparent conductive film on the frame surface. The pressure block 9 is screwed to the frame 8 by a screw 17. The pressure block 10 is a member constituting a hinge structure and is screwed to the frame 8 by a screw 18. The positioning pin 11 is inserted into the pressure block 10 in the Y-axis direction.

[0096] Figure 22 is Figure 7 a cross-sectional view of the ionization device 300 and the frame 8 in the XZ plane as shown. The space 30 formed inside the ionization device 300 is a space including the region where the discharge electrode 6 and the discharge plate 4 face each other. The volume of the space 30 is, for example, 2550 mm when the size of the concave portion 1a is a depth of 6 mm, a horizontal width of 17 mm, and a longitudinal width of 25 mm 3However, the volume of the space 30 is not limited thereto, and it is sufficient as long as it is a volume that can generate a quantity of ionized substances required for analysis using the mass spectrometry device 200 while ensuring a region where the discharge electrode 6 and the discharge plate 4 face each other. For example, it is preferably 10 mm 3 ~4000 mm 3 , more preferably 100~3000 mm 3 , and even more preferably 500~2600 mm 3 .

[0097] As described above, in the present embodiment, the ion formation part can be formed in a small space. One of the reasons is that an opening is formed in the discharge plate as the discharge electrode, and the discharge plate has the function of forming a partition (wall) of the space. In addition, in the opening (4a) of the discharge plate, its end (edge) forms the discharge electrode and a pair of electrodes, and the inside of the hole can have the function of a transfer part for transferring the ionized analysis substance (33a). Therefore, the ionization device can be further miniaturized.

[0098] "GP" in the figure is the distance between the electrodes, and the distance between the electrodes GP is equal to the shortest distance from the front end of the discharge electrode 6 to the discharge plate 4. The concave part 1a of the insulating plate 1 and the end face 2g of the insulating plate 2 function as a space forming part for forming the space 30. The tube 12 functions as an introduction part for introducing the substance to be analyzed by the mass spectrometry device 200 into the space 30. In addition, the space 30 communicates with the outside of the insulating plate 1 and the insulating plate 2 through the tube 12, so it is a semi-closed space having a substance inlet. The through-hole 4a formed by the discharge plate 4 and the through-hole 1b of the insulating plate 1 function as a transfer part for transferring the ionized substance to the mass spectrometry device 200.

[0099] Next, a method for ionizing a substance using the ionization device 300 will be described.

[0100] Figure 23 It is a flowchart for explaining a method for ionizing a substance using the mass spectrometry device 200.

[0101] By operating the gas suction device 400 (step S1), a negative pressure is generated in the space (ion formation part) 30, and the substance 32 to be analyzed by the mass spectrometry device 200 is induced into the space 30 including the region 31 (step S2). At this time, air is also introduced together with the substance 32 as the analysis sample. In addition, the gas sucked together with the substance 32 can be an inert gas such as nitrogen depending on the type of the substance. In the present embodiment, air can be used as the suction gas, so the device is not complicated, and in addition, the operating cost can be reduced.

[0102] The material 32 induced into the space 30 is ionized by the corona discharge 33 generated between the discharge electrode 6 and the discharge plate 4 (step S3).

[0103] The ionized material 33a, which is the ionized substance in the space 30, is transferred to the mass spectrometry device 200 through the through-hole 4a of the discharge plate 4 and the through-hole 1b of the insulating plate 1 (step S4). The principle of transporting the ionized material 33a to the mass spectrometry device 200 is as follows: First, it is attracted by the potential difference and further introduced by the differential pressure. When attracting by the potential difference, the ion inlet 201 is set to a potential opposite to the sign of the charge of the ions of the ionized material 33a, so a part of the ionized material 33a accumulates around the ion inlet 201. In addition, when introducing by the differential pressure, the mass spectrometry device 200 is provided with a gas suction device (not shown), and through the operation of this gas suction device, the ionized material 33a existing around the ion inlet 201 is taken into the mass spectrometry device 200.

[0104] Next, with reference to Figures 24 to 26 , the ion detection intensity (hereinafter sometimes referred to as "ion intensity") using the mass spectrometry device 200 in the case of using the ionization device 300 according to this embodiment will be described.

[0105] Figure 24 It is a graph showing the change of the ion detection intensity with respect to the electrode distance in a state where the discharge voltage is set to 2.0 kV. Figure 25 It is a graph showing the change of the ion detection intensity with respect to the electrode distance in a state where the discharge voltage is set to 2.5 kV. Figure 26 It is a graph showing the change of the ion detection intensity with respect to the electrode distance in a state where the discharge voltage is set to 3.0 kV. Figures 24 to 26 It is the result of an experiment for measuring the change of the ion intensity when the electrode distance is made to approach from 3 mm to 0 mm at a constant speed. The horizontal axis of each of these graphs represents the elapsed time (minutes) and the electrode distance (mm) in parallel double axes. In addition, the vertical axis of each graph represents the ion intensity at each elapsed time and each electrode distance.

[0106] Figures 24 to 26 In each of the graphs of , until 0.5 minutes have elapsed, the electrode distance is 3.0 mm. After 0.5 minutes have elapsed, the electrode distance approaches at a constant speed. When 1.5 minutes have elapsed, the electrode distance becomes 2 mm. When 2.5 minutes have elapsed, the electrode distance becomes 1 mm. After 3.5 minutes, the electrode distance becomes 0 mm.

[0107] Figure 24As shown, when the discharge voltage is 2.0 kV, no discharge occurs, so the ionized substance 33a cannot be observed.

[0108] In contrast, Figure 25 and Figure 26 As shown, when the discharge voltage is 2.5 kV or higher, discharge occurs, so the ionized substance 33a can be observed.

[0109] Figure 25 As shown, when the discharge voltage is 2.5 kV, if the distance between the electrodes approaches 1.5 mm (2.0 minutes), the ion intensity starts to increase. In the range of the distance between the electrodes from 1.3 mm to 0.6 mm (2.2 minutes to 2.9 minutes), the ion intensity maintains the first value (about 0.6×10 7 ). If the distance between the electrodes approaches less than 0.6 mm, the ion intensity starts to decrease from the first value. And if the distance between the electrodes is 0.4 mm (3.1 minutes) or less, the ion intensity maintains the second value (about 0.2×10 7 ). In other words, when the distance between the electrodes is less than 0.5 mm, the ion intensity is relatively low, but it can be detected and observed to a certain extent. When the distance between the electrodes is in the range of 0.5 mm to 1.5 mm, the ion intensity is relatively high. If the distance between the electrodes is 1.5 mm or more, the ion intensity cannot be observed.

[0110] Figure 26 As shown, when the discharge voltage is 3.0 kV, if the distance between the electrodes approaches 2.6 mm (0.9 minutes), the ion intensity starts to increase. In the range of the distance between the electrodes from 2.4 mm to 1.3 mm (0.9 minutes to 2.2 minutes), the ion intensity maintains the first value (about 0.4×10 7 ). In the range of the distance between the electrodes from 1.3 mm to 0.5 mm (2.2 minutes to 3.0 minutes), the ion intensity increases until the second value (about 0.6×10 7 ) and maintains this value. If the distance between the electrodes approaches less than 0.5 mm, the ion intensity starts to decrease from the second value. And if the distance between the electrodes is 0.3 mm (3.2 minutes) or less, the ion intensity maintains the third value (about 0.2×10 7 ). In other words, when the distance between the electrodes is less than 0.5, the ion intensity is relatively low, but it can be detected and observed to a certain extent. When the distance between the electrodes is in the range of 0.5 mm to 1.3 mm, the ion intensity becomes the maximum value. When the distance between the electrodes is in the range of 1.3 mm to 2.6 mm, the ion intensity is lower than the maximum value but becomes a relatively high value. If the distance between the electrodes is 2.6 mm or more, the ion intensity cannot be observed.

[0111] If the ion detection intensity at a discharge voltage of 2.5 kV is compared with the ion detection intensity at a discharge voltage of 3.0 kV, it can be seen that the ion detection intensity at an electrode gap of 2.0 mm (after 1.5 minutes) is higher at 3.0 kV. However, the ion detection intensity near an electrode gap of 1.0 mm (near 2.5 minutes) is at the same level for any discharge voltage.

[0112] As a result, in the ionization device 300 according to the present embodiment, it is preferable to set the discharge voltage to 3.0 kV, and the electrode gap is set to 0.5 to 2.4 mm, preferably 0.5 to 1.3 mm, more preferably the electrode gap is 0.7 to 1.3 mm, and further preferably 0.9 to 1.1 mm. In addition, when the discharge voltage is set to 2.5 kV, it is preferable to set the electrode gap to 0.7 to 1.3 mm, and more preferably to 0.9 to 1.1 mm. However, if the ionization device 300 comes into contact with the ion inlet 201, the electrode gap becomes shorter due to the positional deviation of the discharge plate 4, and there is a concern that corona discharge cannot be generated. Therefore, it is more preferable to consider the installation tolerance of the ionization device 300, and the electrode gap is set to around 1.5 mm (1.3 to 1.7 mm). In addition, if the voltage is excessively increased, the corona discharge changes to arc discharge, and sometimes it is not suitable for ionization. Even when the discharge voltage is 2 kV, sufficient ionization can sometimes be confirmed.

[0113] Next, with reference to Figure 27 and Figure 28 , the comparison results between the ionization device 300 according to the present embodiment and the prior art will be described.

[0114] Figure 27 is a graph showing the change in the ion detection intensity using the ionization device 300 according to the present embodiment with respect to the electrode gap. Figure 28 is a graph showing the change in the ion detection intensity using the prior art with respect to the electrode gap. Figure 27 , Figure 28 is the result of an experiment in which the electrode gap is fixed at 1.5 mm and the change in the ion intensity is measured as the discharge voltage is changed in the order of 2.0 kV, 2.5 kV, and 3.0 kV. In this experiment, in the interval of 0 to 1 minute, the discharge voltage is set to 2.0 kV, in the interval of 1 to 2 minutes, it is set to 2.5 kV, and in the interval of 2 to 3 minutes, it is set to 3.0 kV. The horizontal axis of each of these graphs represents the elapsed time (minutes), and the vertical axis represents the ion detection intensity.

[0115] Figure 27 As shown, according to the ionization device 300, ions can be detected if the discharge voltage is 2.5 kV or more. In contrast, in the prior art, Figure 28As shown, even when the same discharge voltage is applied, only weak ions can be detected. Figure 28 In [reference], it shows a graph at 400 °C in the normal He measurement mode in DART (Direct Analysis in Real Time) which is a conventional ion source.

[0116] Figure 29 It is a graph for charting the mass distribution of ions generated by the ionization device 300 according to the present embodiment. Figure 30 It is a graph for charting the mass distribution of ions generated by the prior art. These graphs are graphs for charting the m / z of ions. The horizontal axis of each of these graphs represents the m / z of the ions. "m / z" is a "dimensionless quantity" obtained by dividing the mass of an ion by the unified atomic mass unit and further dividing by the charge number of the ion. m is the unit representing the mass of the ion in atomic mass units u, and z represents the charge number of the ion. The vertical axis represents the intensity of the ions.

[0117] If the peaks of the background components observed using the ionization device 300 and the prior art are compared, the detected peaks are at approximately the same level, but it can be seen that their intensity ratios are different.

[0118] Figure 31 It is a graph showing the measurement results when the volatile substances generated from a sample (such as beer) are ionized using the ionization device 300 according to the present embodiment. Figure 32 It is a graph showing the measurement results when the volatile substances generated from a sample (such as beer) are ionized using the prior art. The horizontal axis of each of these graphs represents the m / z of the ions, and the vertical axis represents the intensity of the ions.

[0119] According to Figure 31 and Figure 32 , the detected components are the same, but the ion intensity using the ionization device 300 is about 10 times that of the prior art. This is because it is possible to approach the distance from the ionization point of the volatile substance to the ion inlet 201, and it is considered that a large reason is that the diffusion of the ionized substance 33a can be prevented by the space 30. In addition, the distance from the ion inlet 201 to the ion generation part (ionization point) is, for example, 5 mm.

[0120] Figure 33 It is a graph showing the correspondence relationship between the discharge voltage set when ionized using the ionization device 300 according to the present embodiment and the distance between the electrodes.

[0121] When the discharge voltage is 2.0 kV, no discharge occurs, so regardless of the size of the distance between the electrodes, the ionized substance 33a cannot be observed.

[0122] When the discharge voltage is 2.5 kV, the ionized substance 33a can be observed when the distance between the electrodes is an extremely small interval (e.g., about 0.1 to 0.2 mm), 1 mm, etc., but when the distance between the electrodes is 2 mm, the ionized substance 33a cannot be basically observed, and when the distance between the electrodes is 3 mm, the ionized substance 33a cannot be observed.

[0123] When the discharge voltage is 3.0 kV, the ionized substance 33a can be observed when the distance between the electrodes is an extremely small interval (e.g., about 0.1 to 0.2 mm), 1 mm, 2 mm, etc., but when the distance between the electrodes is 3 mm, the ionized substance 33a cannot be basically observed.

[0124] As described above, according to the ionization device 300 according to the present embodiment, an insulating portion is provided outside the mass spectrometry device 200, and corona discharge can be generated in the small space 30 formed by the insulating portion. Therefore, the diffusion of the ionized substance can be suppressed. In addition, by providing the discharge plate 4 on the insulating plate 1 disposed opposite to the ion introduction port 201, the region 31 where the discharge electrode 6 is opposed to the discharge plate 4 can be provided near the ion introduction port 201. Therefore, the distance from this region 31 to the ion introduction port 201 can be as short as, for example, about several mm. Therefore, according to the ionization device 300, the sample before ionization can be ionized without diffusion, and the ionized sample can be quickly sent to the mass spectrometry device 200. That is, the highly concentrated ionized substance 33a whose diffusion to the outside (open space) of the insulating portion is suppressed can be quickly transferred to the ion introduction port 201 while suppressing the concentration decrease. As a result, the analysis responsiveness and analysis sensitivity of the mass spectrometry device 200 are greatly improved.

[0125] In addition, the discharge plate 4 disposed on the insulating plate 1 is grounded, so that the mass spectrometry device 200 can detect an abnormal voltage and suppress the operation stop.

[0126] In addition, by disposing the discharge plate 4 in the concave portion 1a formed by the insulating plate 1, the distance from the region 31 where the discharge electrode 6 is opposed to the discharge plate 4 to the ion introduction port 201 can be further shortened. Thereby, while ensuring electrical insulation from the mass spectrometry device 200, the concentration decrease of the substance that can be transferred to the mass spectrometry device 200 can be further suppressed. As a result, compared with the case where the concave portion 1a is not provided on the insulating plate 1, the analysis responsiveness and analysis sensitivity of the mass spectrometry device 200 are further improved.

[0127] Furthermore, by disposing a discharge plate (ground potential electrode) 4 immediately in front of the ion introduction port 201 of the mass spectrometry device, for example, even if an arc discharge occurs between the electrodes due to overvoltage application, no current flows through the mass spectrometry device itself. Therefore, there is no association with a failure of the mass spectrometry device, and safety can be ensured. In addition, in the mass spectrometry device, there are cases where the ion introduction section (ion introduction port) is maintained in a high voltage form, and sometimes voltage adjustment of the ion source itself is required. However, the ion source of the present embodiment does not require voltage adjustment using the relationship with the mass spectrometry layer.

[0128] In addition, in the ionization device 300 according to the present embodiment, as in the prior art, even without using a carrier gas (inert gas such as helium), by introducing the substance 32 as an analysis sample and air into the space 30, the ionized substance 33a can be easily obtained.

[0129] In addition, with this configuration, it is easy to manage the sample collection amount (suction amount) for the space 30, and analysis using the mass spectrometry device 200 can be easily performed.

[0130] In addition, with this configuration, even at normal temperature and / or atmospheric pressure, the ionized substance can be easily generated. In the prior art, for example, a heater is provided to prevent the ionized substance from adhering to the Ni capillary of the ion source unit. In contrast, the ionization device 300 according to the present embodiment does not require a heater. As a result, the configuration of the mass spectrometry system 100 is simplified, the reliability of the system is improved, and the cost required for constructing the system can be reduced.

[0131] In addition, with this configuration, direct analysis of the sample is possible without spraying the sample as in the prior art.

[0132] In addition, in the present embodiment, corona discharge (direct current corona discharge) is performed using the DC power supply 700, but corona discharge (alternating current corona discharge) can be performed using an AC power supply instead of the DC power supply 700. When using the DC power supply 700, the power supply of the mass spectrometry device 200 can be shared. Therefore, the configuration of the mass spectrometry system 100 is simplified, the reliability of the system is improved, and the cost required for constructing the system can be reduced. In addition, when using an AC power supply, effects such as being easily seen in the case of obtaining an alternating current through the ionized substance can be obtained.

[0133] In addition, the ionization method according to this embodiment is formed by a first insulating portion and a second insulating portion provided between the first insulating portion and the mass spectrometry device, and induces a substance to be analyzed by the mass spectrometry device in a space in a region where a first electrode provided on the first insulating portion and a second electrode provided on the second insulating portion face each other, and ionizes the induced substance in the space by corona discharge generated between the first electrode and the second electrode.

[0134] The configuration shown in the above embodiment represents an example of the content of the present disclosure, and can also be combined with other known technologies, and a part of the configuration can be omitted or changed without departing from the gist of the present disclosure.

[0135] This international application claims the priority based on Japanese Patent Application No. 2020-029310 filed on February 25, 2020, and incorporates the entire content of 2020-029310 into this international application.

[0136] Explanation of reference numerals

[0137] 1: Insulating plate;

[0138] 1b: Through hole (transfer portion);

[0139] 2: Insulating plate;

[0140] 4: Discharge plate;

[0141] 4a: Opening (transfer portion);

[0142] 6: Discharge electrode;

[0143] 12: Tube;

[0144] 30: Space (ion formation portion);

[0145] 31: Region;

[0146] 32: Substance;

[0147] 33: Corona discharge;

[0148] 33a: Ionized substance;

[0149] 100: Mass spectrometry system;

[0150] 200: Mass spectrometry device;

[0151] 201: Ion intake port;

[0152] 300: Ionization device;

[0153] 400: Gas suction device.

Claims

1. An ionization device, comprising: an ion formation unit that ionizes an analyte by corona discharge; and a transfer unit that transfers the ionized analyte to a mass spectrometry device, wherein the ion formation unit and the transfer unit are separated by one of a pair of electrodes that generates the corona discharge and has an opening, and the ionization device further comprises: a tube for supplying the analyte, which opens into a region where the corona discharge is generated inside the ion formation unit; and a gas suction device that communicates with a space including the ion formation unit at a position downstream of the one electrode in the transfer direction of the ionized analyte by the transfer unit, wherein when a negative pressure is generated in the ion formation unit by operation of the gas suction device, the analyte is supplied from the tube to the region where the corona discharge is generated, the ion formation unit is a semi-closed space that communicates with the outside via the tube serving as an introduction port for the analyte, the discharge voltage when the pair of electrodes generate the corona discharge is 2.5 kV or more, when the discharge voltage is 2.5 kV or 3.0 kV, the distance between the pair of electrodes is in the range of 0.9 to 1.1 mm.

2. The ionization device according to claim 1, wherein the opening of the one electrode and the ion inlet of the ionized analyte of the mass spectrometry device are arranged on a straight line.

3. A mass spectrometry system, comprising: the ionization device according to claim 1 or 2, and the mass spectrometry device.

4. A method for ionizing an analyte, wherein the ion formation unit and the transfer unit are separated by one of a pair of electrodes that generates the corona discharge and has an opening, the ion formation unit ionizes the analyte by the corona discharge, and the transfer unit transfers the ionized analyte to a mass spectrometry device, a negative pressure is generated in the ion formation unit by operation of a gas suction device, the gas suction device communicates with a space including the ion formation unit at a position downstream of the one electrode in the transfer direction of the ionized analyte by the transfer unit, the analyte is supplied from a tube that opens into a region where the corona discharge is generated inside the ion formation unit to the region where the corona discharge is generated by the negative pressure and ionized, the ion formation unit is a semi-closed space that communicates with the outside via the tube serving as an introduction port for the analyte, the discharge voltage when the pair of electrodes generate the corona discharge is 2.5 kV or more, when the discharge voltage is 2.5 kV or 3.0 kV, the distance between the pair of electrodes is in the range of 0.9 to 1.1 mm.

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