A zoned non-uniform field photoionization and / or photochemical ionization source

Abstract

The present application relates to mass spectrometry instrument, specifically to a kind of partition non-uniform field photoionization and / or photochemical ionization source device that can realize reagent sufficient ionization, including ultraviolet light source, ion repulsion electrode, isolation electrode, ion transmission electrode, ion focusing electrode, ion source outlet electrode, sample introduction capillary, side extraction valve and ion source cavity;Ion repulsion electrode, isolation electrode, ion transmission electrode, ion focusing electrode and ion source outlet electrode are placed in parallel, insulated, coaxial in ion source cavity, wherein isolation electrode and ion focusing electrode divide ionization zone into three chambers, respectively reagent ion generation zone, ion molecular reaction zone and ion focusing zone. By changing the electric field intensity of reagent ion generation zone, the rapid switching of photoionization or photochemical ionization can be realized. The isolation electrode is a convex electrode with a central through hole and an edge thickness of 1-10 mm. By increasing the thickness of the isolation electrode and appropriately reducing the size of the central through hole, the influence of sample gas backflow on the ionization process of reagent molecules can be effectively avoided. Secondly, one or more ion transmission electrodes are added in the reagent ion generation zone, which can make the reagent molecules fully photoionize, produce high-intensity and high-purity reagent ions, and thus effectively improve the sensitivity of the analyte analysis. The device can be used with any type of mass analyzer to achieve high-sensitivity and rapid detection of various trace volatile components.

Description

Technical Field

[0001] This invention relates to mass analysis instruments, and particularly to ionization sources for mass spectrometers, specifically a partitioned, highly sensitive photoionization and / or photochemical ionization source capable of fully ionizing reagent molecules. Background Technology

[0002] Mass spectrometry (MS) is a technique that separates and analyzes components based on their mass-to-charge ratio. Its basic principle is that the components in the sample are ionized in an ion source, generating ions with different mass-to-charge ratios. These ions are then guided or accelerated by an electric field, forming ion beams with different initial velocities. These beams enter the mass analyzer, where an electric or magnetic field completes the mass separation process, producing a mass spectrum. From the mass spectrum, the elemental composition of each component in the sample can be deduced based on the measured mass-to-charge ratio. Mass spectrometry offers advantages such as high sensitivity, fast analysis speed, easy spectrum interpretation, and a wide range of analyzable compounds, making it widely used for rapid online detection of complex mixed samples. The ion source is one of the core components of mass spectrometry, responsible for sample ionization and closely related to the achievable sensitivity. Ultraviolet photoionization is a highly efficient "soft" ionization technique, a threshold ionization technique. Only compound molecules with an ionization energy (IE) lower than the photon energy are ionized after absorbing photons. Since the photon energy absorbed by the analyte molecules is only slightly higher than their ionization energy, photoionization generates a large number of molecular ions. Combining these with a mass analyzer allows for rapid online qualitative and quantitative analysis of complex samples [Chinese Invention Patent: 201611039752.4]. However, due to limitations in the material of the optical window, the highest energy of photons that can currently pass through is 11.8 eV. Compounds with ionization energies higher than 11.8 eV (such as methane, IE = 12.61 eV; acetonitrile, IE = 12.2 eV, etc.) cannot be effectively ionized, which limits the application areas of photoionization source mass spectrometry. Photochemical ionization (PDI) is another highly efficient "soft" ionization technique. Its principle is as follows: First, a reagent gas is selected based on the properties of the sample to be tested. High-intensity reagent ions are generated through photoionization or photoelectron ionization. These reagent ions then react with sample molecules to achieve ionization of the analyte molecules [Chinese Invention Patent: 201811381275.9]. PII produces fewer fragment ions, resulting in simpler mass spectra and higher sensitivity. PII can achieve various types of ion-molecule reactions, including proton transfer, charge transfer, electrophilic addition, and anion extraction. Analytes with different properties can be effectively ionized using different types of ion-molecule reactions. However, there is usually no strict boundary between the reagent ion generation region and the analyte ionization region. This allows sample gas to flow back into the reagent ion generation region, and the matrix in the sample, such as humidity, can affect the ionization of reagent ions, thus impacting the sensitivity of PII.

[0003] Therefore, this invention designs a non-uniform field photoionization and / or photochemical ionization source that can achieve sufficient photoionization of reagent molecules. Based on a single ultraviolet light source, chemically ionized reagent ions are obtained by photoionization or photoelectron ionization. Different reagent ions can be obtained by changing the type of reaction gas. Through the unique design of the isolation electrode structure, the individual ionization of reagent gas is realized, reducing the influence of sample gas backflow on the reagent ion ionization process. Secondly, in the reagent ion generation region, one or more transport ionization electrodes are added to achieve sufficient photoionization of reagent molecules, so as to generate high-intensity and high-purity reagent ions. Summary of the Invention

[0004] The purpose of this invention is to provide a partitioned non-uniform field photoionization and / or photochemical ionization source that can achieve sufficient photoionization of reagent molecules. Based on a single ultraviolet light source, it enables rapid switching of different reagent ions to broaden the range of ionizable and detectable samples. Through a unique design of the isolation electrode structure, it achieves individual ionization of reagent gas, reducing the impact of sample gas backflow on the reagent ion ionization process. Furthermore, in the reagent ion generation region, one or more transport ionization electrodes are added to achieve sufficient photoionization of reagent molecules, thereby generating high-intensity and high-purity reagent ions.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A partitioned non-uniform field photoionization and / or photochemical ionization source device includes an ultraviolet light source, a reaction gas inlet tube, a sample gas inlet tube, and an ionization source cavity. The ionization source cavity is a hollow sealed chamber with a through hole at the top. The light window of the ultraviolet light source extends into the ionization source cavity through the through hole, and the ultraviolet light source is sealed to the through hole.

[0007] Inside the ionization source cavity, along the emission direction of the ultraviolet beam emitted by the ultraviolet light source, an ion repulsion electrode, an ion transport electrode, an isolation electrode, an ion focusing electrode, and an ionization source outlet electrode are arranged sequentially. All of these electrodes are annular structures with through holes in the middle, and they are spaced apart and placed parallel to each other by annular insulating gaskets with through holes in the middle. The through holes of the electrodes and the insulating gaskets are coaxial. The insulating gaskets are sealed to the adjacent electrode plates.

[0008] The lower opening of the central through-hole of the isolation electrode is provided with a convex electrode with an annular protrusion coaxial with the through-hole, which can effectively prevent sample gas backflow and affect the ionization of reagent ions; the ultraviolet beam passes through each electrode through-hole along the axial direction of the electrode.

[0009] The outlet electrode (6) can also be called the Skimmer 1 electrode or the Sampler electrode;

[0010] The isolation electrode and the ion focusing electrode divide the ionization region between the ion repulsion electrode and the exit electrode into three chambers along the ultraviolet beam emission direction: the reagent ion generation region between the repulsion electrode and the isolation electrode, the ion molecular reaction region between the isolation electrode and the ion focusing electrode, and the ion focusing region between the ion focusing electrode and the ionization source exit electrode.

[0011] The reaction gas inlet tube passes through the outer wall of the ionization source cavity, and its gas outlet end extends into the reagent ion generation region. The outlet end faces the gap between the repulsion electrode and the ion transport electrode plate near the repulsion electrode. Its gas outlet end is set facing the ultraviolet beam irradiation area. The reaction gas generates reagent ions or sample ions in the area through which the ultraviolet beam passes. The reagent ions or sample ions pass through the central through hole of the isolation electrode and enter the ion molecule reaction region. The gas inlet end of the reaction gas inlet tube is connected to the reaction gas source or sample gas source.

[0012] The sample gas inlet tube passes through the outer wall of the ionization source cavity, and its gas outlet end extends into the interior of the ion molecular reaction zone. The outlet end faces the gap between the isolation electrode and the ion transport electrode plate near the isolation electrode. Its gas outlet end is set facing the side wall of the annular protrusion. The gas inlet end of the sample gas inlet tube is connected to the sample gas source; sample ions are generated in the ion molecular reaction zone.

[0013] A through hole A is provided at the bottom of the ionization source cavity, and the ionization source outlet electrode is sealed to the bottom of the ionization source cavity; the circular through hole of the ionization source outlet electrode is provided corresponding to through hole A, that is, the sample ions pass through the circular through hole and through hole A of the ionization source outlet electrode and leave the ionization source cavity.

[0014] A gas outlet is provided on the side wall of the ionization source cavity. The gas outlet is connected to a vacuum valve through a vacuum line. A vacuum pump is connected to the other end of the side vacuum valve through a vacuum line.

[0015] The axial height of the annular protrusion is 0.8-9.8 mm, and the lower end face of the annular protrusion is located above the plane A on the upper surface of the electrode of the ion transport electrode near the lower part of the isolation electrode. The distance between the lower end face of the annular protrusion and plane A is 0.2-9.2 mm.

[0016] The reagent ion generation region is equipped with one or more ion transport electrodes to enable reagent molecules to undergo sufficient photoionization, thereby generating reagent ions with high intensity and high purity.

[0017] The ultraviolet light source is a gas discharge lamp, a laser light source, or a synchrotron radiation light source.

[0018] A through hole or groove is provided on the insulating sheet between the ion focusing electrode and the ionization source outlet electrode, along the radial direction of the central through hole, to penetrate the inner and outer walls of the insulating sheet and serve as a gas outlet.

[0019] The ion repulsion electrode, ion transport electrode, isolation electrode, ion transport electrode, and ion focusing electrode are all made of stainless steel plates with a thickness of 0.5-10mm, and the inner diameter of the central through hole is 0.5-16mm; the ionization source outlet electrode is a conical stainless steel plate with a central hole diameter of 1mm, and the distance between two adjacent electrode plates is 1-10mm.

[0020] The repulsion electrode and its adjacent ion transport electrode, and the isolation electrode and its adjacent ion transport electrode are all connected by a voltage divider with a resistance of 1-2 MΩ; the reagent ion generation region is provided with one or more ion transport electrodes, and the two or more ion transport electrodes are connected by a voltage divider with a resistance of 1-2 MΩ.

[0021] The same or different voltages are applied to the ion repulsion electrode and the isolation electrode, respectively. The voltage applied to the ion repulsion electrode is greater than or equal to the voltage applied to the isolation electrode. Different voltages are applied to the isolation electrode, the ion focusing electrode and the ion source outlet electrode in descending order. An ion transport gradient electric field of different intensities is formed from top to bottom in the axial direction of the central region of the through hole of each electrode, so that ions are focused and transported toward the central through hole of the ion source outlet electrode. The magnitude of the ion transport gradient electric field is 0-300V / cm.

[0022] The through hole in the middle of the ionization source outlet electrode is an ion outlet hole, and the electrode is connected to the ion inlet of the mass analyzer; the mass analyzer is one of the following: quadrupole mass analyzer, ion trap mass analyzer, magnetic mass analyzer, time-of-flight mass analyzer, or any combination of two or more of the above mass analyzers.

[0023] The internal gas pressure of the ionization source cavity is 10. -3 -10 5 Pa;

[0024] An electric heating element and / or insulation layer are installed on the outer wall of the reaction gas inlet tube and the sample gas inlet tube to control the temperature of the reaction gas and sample gas entering the ionization zone between room temperature and 300°C.

[0025] The reaction gas inlet tube and the sample gas inlet tube can be metal capillaries or quartz capillaries, and there can be one or several; the length is 0.05 to 5 m, and the inner diameter is 25 to 500 μm.

[0026] The ionization source can operate in both photochemical ionization and photoelectric ionization modes. The switching between these modes can be achieved by changing the voltage applied to the repulsive ionization, isolation electrode, and ion focusing electrode, as well as the type of reactant gas.

[0027] The outer wall of the ultraviolet light source is sealed to the inner wall of the through hole, and the periphery of the ionization source outlet electrode is sealed to the inner wall of the through hole A.

[0028] The reaction gas source provided by the reaction gas source is one or more of nitrogen, argon, helium or other rare gases with a mass purity greater than 99.999%, carrying one or more of water vapor, dichloromethane, dibromomethane, oxygen, and nitric oxide.

[0029] The advantages of this method are as follows:

[0030] 1. Compared with photoionization and / or photochemical ionization sources that can achieve in-source focusing, firstly, one or more transport electrodes are added in the reagent ion generation region, which can achieve sufficient photoionization of reagent molecules; secondly, the structure of the isolation electrode is improved, which can effectively reduce the influence of sample gas backflow on the reagent ionization process.

[0031] Both photoionization and chemical ionization modes can be used to quickly cut the ions into blocks, and the reagent ions can be flexibly varied, thus broadening the range of ionizable volatile organic compounds. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the present invention;

[0033] Figure 2 This is to increase the humidity in the sample gas before and after the isolation electrode on CH2Br2. + The effect of reagent ion ionization. Detailed Implementation

[0034] Please see Figure 1 The diagram below shows the structure of the present invention. The present invention is a partitioned non-uniform field photoionization and / or photochemical ionization source device, comprising an ultraviolet light source 1, a reaction gas inlet tube 7, a sample gas inlet tube 8, and an ionization source cavity 9. The ionization source cavity 9 is characterized in that: the ionization source cavity 9 is a hollow, sealed chamber, with a through-hole at the top of the ionization source cavity 9; the light window of the ultraviolet light source 1 extends into the ionization source cavity 9 through the through-hole, and the ultraviolet light source 1 is sealed to the through-hole.

[0035] Inside the ionization source cavity 9, along the emission direction of the ultraviolet beam emitted by the ultraviolet light source 1, an ion repulsion electrode 2, an ion transport electrode 4, an isolation electrode 3, an ion transport electrode 4, an ion focusing electrode 5, and an ionization source outlet electrode 6 are arranged sequentially. All of these electrodes are annular structures with through holes in the middle, and they are spaced apart and placed parallel to each other by annular insulating pads with through holes in the middle. The through holes of the electrodes and the insulating pads are coaxial. The insulating pads are sealed to the adjacent electrode plates.

[0036] The lower opening end of the central through hole of the isolation electrode 3 is provided with a convex electrode with an annular protrusion coaxial with the through hole, which can effectively prevent sample gas backflow and affect the ionization of reagent ions; the ultraviolet beam passes through each electrode through hole along the axial direction of the electrode.

[0037] The isolation electrode 3 and the ion focusing electrode 5 divide the ionization region between the ion repulsion electrode 2 and the outlet electrode 6 into three chambers along the ultraviolet beam emission direction: the reagent ion generation region 15 located between the repulsion electrode 2 and the isolation electrode 3, the ion molecule reaction region 16 located between the isolation electrode 3 and the ion focusing electrode 5, and the ion focusing region 17 located between the ion focusing electrode 5 and the ionization source outlet electrode 6.

[0038] The reaction gas inlet tube 7 passes through the outer wall of the ionization source cavity 9, and its gas outlet end extends into the reagent ion generation region 15. The outlet end faces the space between the repulsion electrode 2 and the ion transport electrode 4 near the repulsion electrode 2. Its gas outlet end is set facing the ultraviolet beam irradiation area. The reaction gas generates reagent ions or sample ions in the ultraviolet beam passing area. The reagent ions or sample ions pass through the middle through hole of the isolation electrode 3 and enter the ion molecule reaction region 16. The gas inlet end of the reaction gas inlet tube 7 is connected to the reaction gas source 12 or the sample gas source 13.

[0039] The sample gas inlet tube 8 passes through the outer wall of the ionization source cavity 9, and its gas outlet end extends into the interior of the ion molecular reaction zone 16. The outlet end faces the gap between the isolation electrode 3 and the ion transport electrode 4 plate near the isolation electrode 3. Its gas outlet end is set facing the side wall of the annular protrusion. The gas inlet end of the sample gas inlet tube 8 is connected to the sample gas source 13; sample ions are generated in the ion molecular reaction zone 16.

[0040] A through hole A is provided at the bottom of the ionization source cavity 9, and the ionization source outlet electrode 6 is sealed to the bottom of the ionization source cavity 9; the circular through hole of the ionization source outlet electrode 6 is provided corresponding to the through hole A, that is, the sample ions pass through the circular through hole and through hole A of the ionization source outlet electrode 6 and leave the ionization source cavity 9.

[0041] A gas outlet is provided on the side wall of the ionization source cavity 9. The gas outlet is connected to a vacuum valve 10 through a vacuum pipeline. A vacuum pump 11 is connected to the other end of the side valve through a vacuum pipeline.

[0042] The axial height of the annular protrusion is 0.8-9.8 mm, and the lower end face of the annular protrusion is located above the plane A on the upper surface of the electrode of the ion transport electrode near the lower part of the isolation electrode. The distance between the lower end face of the annular protrusion and plane A is 0.2-9.2 mm.

[0043] The reagent ion generation region 15 is provided with one or more ion transport electrodes 4, the purpose of which is to enable reagent molecules to undergo sufficient photoionization in order to generate reagent ions with high intensity and high purity.

[0044] The ultraviolet light source 1 is a gas discharge lamp light source, a laser light source, or a synchrotron radiation light source.

[0045] A through hole or groove is provided on the insulating sheet between the ion focusing electrode 5 and the ion source outlet electrode 6, along the radial direction of the central through hole, to serve as a gas outlet, penetrating the inner and outer walls of the insulating sheet.

[0046] The ion repulsion electrode 2, ion transport electrode 4, isolation electrode 3, ion transport electrode 4, and ion focusing electrode 5 are all made of stainless steel plates with a thickness of 0.5-10mm, and the inner diameter of the central through hole is 0.5-16mm; the ion source outlet electrode 6 is a conical stainless steel plate with a central hole diameter of 1mm, and the distance between two adjacent electrode plates is 1-10mm.

[0047] The repulsion electrode 2 and its adjacent ion transport electrode 4, and the isolation electrode 3 and its adjacent ion transport electrode 4 are all connected by a voltage divider with a resistance of 1-2 MΩ; the reagent ion generation region 15 is provided with one or more ion transport electrodes 4, and the two or more ion transport electrodes are connected by a voltage divider with a resistance of 1-2 MΩ.

[0048] The same or different voltages are applied to the ion repulsion electrode 2 and the isolation electrode 3 respectively. The voltage applied to the ion repulsion electrode 2 is greater than or equal to the voltage applied to the isolation electrode 3. Different voltages are applied to the isolation electrode 3, the ion focusing electrode 5 and the ion source outlet electrode 6 in descending order. Different ion transport gradient electric fields of different intensities are formed from top to bottom in the axial direction of the central region of the through hole of each electrode, so that ions are focused and transported toward the central through hole of the ion source outlet electrode 6. The magnitude of the ion transport gradient electric field is 0-300V / cm.

[0049] The through hole in the middle of the ionization source outlet electrode 6 is an ion outlet hole, which is connected to the ion inlet of the mass analyzer 18; the mass analyzer 18 is one of a quadrupole mass analyzer, an ion trap mass analyzer, a magnetic mass analyzer, a time-of-flight mass analyzer, or any combination of two or more of the above mass analyzers.

[0050] The reaction gas inlet tube 7 and the sample gas inlet tube 8 can be metal capillaries or quartz capillaries, and can be one or several; the length is 0.05 to 5 m and the inner diameter is 25 to 500 μm.

[0051] The ionization source can operate in two modes: photochemical ionization and photoelectroionization. The switching between these modes can be achieved by changing the voltage applied to the repulsive ionization 2, the isolation electrode 3, and the ion focusing electrode 5, as well as the type of reaction gas.

[0052] The outer wall of the ultraviolet light source 1 is sealed to the inner wall of the through hole, and the four edges of the ionization source outlet electrode 6 are sealed to the inner wall of the through hole A.

[0053] The reaction gas provided by the reaction gas source 12 is one or more of nitrogen, argon, helium or other rare gases with a mass purity greater than 99.999%, carrying one or more of water vapor, dichloromethane, dibromomethane, oxygen and nitric oxide.

[0054] In specific implementation, electric heating elements and / or insulation layers 14 are installed on the outer walls of the protective gas inlet tube 7 and the sample gas inlet tube 8 to control the gas temperature entering the ionization zone between room temperature and 300℃. The heated gas effectively prevents the adsorption and precipitation of gas molecules on the inner wall of the inlet tube. Different voltages are sequentially applied to the ion repulsion electrode 2, ion acceleration electrode 3, ion focusing electrode 5, and ionization source outlet electrode 6 in descending order of voltage. This creates ion transport gradient electric fields of varying intensities along the axial direction of the central region of each electrode through-hole, causing ions to focus and transport towards the central through-hole of the ionization source outlet electrode 6. The magnitude of the ion transport gradient electric field is 0-300V / cm. By adjusting the opening and closing degree of the side-extraction valve 10 connected to the gas outlet on the side wall of the ionization zone cavity 9, the working gas pressure of the ionization zone cavity 9 can be conveniently adjusted within the range of 10-1000Pa to achieve efficient photoionization and / or photochemical ionization under different gas pressures and modes. Taking the photoionization of CH2Br2 reagent gas as an example, such as Figure 2 As shown, this illustrates the effect of different humidity levels on CH2Br2. + The effect of reagent ion ionization: Compared with the photoionization source without isolation electrode 3, the improved ionization source with isolation electrode 3 shows that CH2Br2... + The photoionization process of reagent ions is significantly less affected by the humidity of the sample atmosphere.

Claims

1. A zoned non-uniform field photoionization and / or photo-chemical ionization source apparatus comprising an ultraviolet light source (1), a reactant gas inlet tube (7), a sample gas inlet tube (8), an ionization source cavity (9), characterized in that: The ionization source cavity (9) is a hollow sealed chamber, a through hole is arranged on the top of the ionization source cavity (9), the light window of the ultraviolet light source (1) extends into the ionization source cavity (9) through the through hole, and the ultraviolet light source (1) is in sealed connection with the through hole; Inside the ionization source cavity (9), the ion repulsion electrode (2), the ion transmission electrode (4), the isolation electrode (3), the ion transmission electrode (4), the ion focusing electrode (5) and the ionization source outlet electrode (6) are sequentially arranged along the direction of the ultraviolet light beam emitted by the ultraviolet light source (1); the electrodes are all annular structures with through holes in the middle, and they are spaced apart and placed in parallel through annular insulating pads with through holes in the middle, and the through holes of the electrodes and the insulating pads are coaxial; the insulating pads are in sealed connection with the adjacent electrode plates; The lower opening end of the central through hole of the isolation electrode (3) is provided with a convex electrode with a ring-shaped protrusion coaxial with the through hole, which can effectively prevent the backflow of sample gas and affect the ionization of reagent ions; the ultraviolet light beam passes through the through holes of the electrodes along the axial direction of the electrodes; The isolation electrode (3) and the ion focusing electrode (5) divide the ionization zone between the ion repulsion electrode (2) and the outlet electrode (6) into three chambers along the direction of the ultraviolet light beam, which are respectively a reagent ion generation zone (15) between the repulsion electrode (2) and the isolation electrode (3), an ion molecule reaction zone (16) between the isolation electrode (3) and the ion focusing electrode (5), and an ion focusing zone (17) between the ion focusing electrode (5) and the ionization source outlet electrode (6); The reaction gas sampling pipe (7) penetrates through the outer wall surface of the ionization source cavity (9), the gas outlet end thereof extends into the reagent ion generation zone (15), the outlet end surface thereof faces the spacing area between the repulsion electrode (2) and the ion transmission electrode (4) plate close to the repulsion electrode (2), and the gas outlet end surface thereof faces the ultraviolet light beam irradiation area, the reaction gas generates reagent ions or sample ions in the ultraviolet light beam passing area, the reagent ions or sample ions enter the ion molecule reaction zone (16) through the middle through hole of the isolation electrode (3), and the gas inlet end of the reaction gas sampling pipe (7) is connected with the reaction gas source (12) or the sample gas source (13); The sample gas sampling pipe (8) penetrates through the outer wall surface of the ionization source cavity (9), the gas outlet end thereof extends into the interior of the ion molecule reaction zone (16), the outlet end surface thereof faces the spacing area between the isolation electrode (3) and the ion transmission electrode (4) plate close to the isolation electrode (3), and the gas outlet end surface thereof faces the side wall surface of the ring-shaped protrusion, and the gas inlet end of the sample gas sampling pipe (8) is connected with the sample gas source (13); sample ions are generated in the ion molecule reaction zone (16); A through hole A is arranged on the bottom of the ionization source cavity (9), the ionization source outlet electrode (6) is in sealed connection with the bottom of the ionization source cavity (9), and the circular through hole of the ionization source outlet electrode (6) is correspondingly arranged with the through hole A, that is, the sample ions pass through the circular through hole of the ionization source outlet electrode (6) and the through hole A to leave the ionization source cavity (9); A gas outlet is arranged on the side wall of the ion source cavity (9), and the gas outlet is connected with an exhaust valve (10) through a vacuum pipeline. A vacuum pump (11) is connected with the other end of the exhaust valve through a vacuum pipeline.

2. The device of claim 1, wherein: The axial height of the annular protrusion is 0.8-9.8 mm, and the lower end surface of the annular protrusion is located above the plane A of the upper surface of the pole piece of the ion transmission electrode below the isolation electrode, and the distance between the lower end surface of the annular protrusion and the plane A is 0.2-9.2 mm.

3. The device of claim 1, wherein: The reagent ion generation area (15) is provided with one or more than two ion transmission electrodes (4) to make the reagent molecules fully photoionize to generate high-intensity and high-purity reagent ions. The ultraviolet light source (1) is a gas discharge lamp light source, a laser light source or a synchrotron radiation light source.

4. The device of claim 1, wherein: A through hole or a groove is arranged on the insulating sheet between the ion focusing electrode (5) and the ion source outlet electrode (6) along the radial direction of the central through hole as a gas outlet.

5. The device of claim 1, wherein: The materials of the ion repulsion electrode (2), the ion transmission electrode (4), the isolation electrode (3), the ion transmission electrode (4), the ion focusing electrode (5) are all stainless steel plates with a thickness of 0.5-10 mm, and the inner diameter of the central through hole is 0.5-16 mm; the ion source outlet electrode (6) is a conical stainless steel plate with a central hole diameter of 1 mm, and the distance between the adjacent two electrode sheets is 1-10 mm; The repulsion electrode (2) and its adjacent ion transmission electrode (4), the isolation electrode (3) and its adjacent ion transmission electrode (4) are all divided by resistors with a resistance of 1-2 MΩ; the reagent ion generation area (15) is provided with one or more than two ion transmission electrodes (4), and the two or more ion transmission electrodes are divided by resistors with a resistance of 1-2 MΩ; Different voltages are loaded on the ion repulsion electrode (2) and the isolation electrode (3) respectively, the voltage loaded on the ion repulsion electrode (2) is greater than or equal to the voltage loaded on the isolation electrode (3), different voltages are loaded on the isolation electrode (3), the ion focusing electrode (5) and the ion source outlet electrode (6) in the order from high to low, and an ion transmission gradient electric field with different intensities is formed in the axial direction of the central area of the through hole of each electrode from top to bottom, so that the ions are focused and transmitted towards the central through hole of the ion source outlet electrode (6), and the size of the ion transmission gradient electric field is 0-300 V / cm.

6. The device of claim 1, wherein: The central through hole of the ion source outlet electrode (6) is an ion outlet hole, and the electrode is connected with the ion inlet of the mass analyzer (18); the mass analyzer (18) is one of a quadrupole rod mass analyzer, an ion trap mass analyzer, a magnetic mass analyzer and a time-of-flight mass analyzer, or a combination of any two or more of the above mass analyzers.

7. The apparatus according to claim 1, characterized in that: The internal pressure of the ionization source cavity (9) is 10 -3 -10 5 Pa; The outer wall of the pipeline of the reaction gas inlet tube (7) and the sample gas inlet tube (8) is provided with an electric heating element and / or a heat preservation layer (14), so as to control the temperature of the reaction gas and the sample gas entering the ionization zone at room temperature-300℃.

8. The apparatus according to claim 1, characterized in that: The reaction gas inlet tube (7) and the sample gas inlet tube (8) can be a metal capillary tube or a quartz capillary tube, and can be one or several; the length is 0.05-5m, and the inner diameter is 25-500μm.

9. The apparatus according to claim 1, characterized in that: The ionization source can work in photochemical ionization and photoionization two modes, by changing the voltage loaded on the repulsion ionization (2), the isolation electrode (3) and the ion focusing electrode (5), and the reaction gas species, the mutual switching can be realized.

10. The apparatus according to claim 1, characterized in that: The outer wall surface of the ultraviolet light source (1) is in close connection with the inner wall surface of the through hole, and the four peripheral edges of the ionization source outlet electrode (6) are in close connection with the inner wall surface of the through hole A; The reaction gas provided by the reaction gas source (12) is one or more than two of nitrogen, argon, helium or other noble gases with mass purity greater than 99.999%, and one or more than two of water vapor, dichloromethane, dibromomethane, oxygen, nitric oxide.

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