A membrane introduction ion funnel ionization source device

Abstract

The application discloses a membrane sample injection ion funnel ionization source device and belongs to the technical field of mass spectrometry analyzers. The device comprises an ionization source cavity, the top of the ionization source cavity is provided with a vacuum ultraviolet lamp, and the bottom of the ionization source cavity is provided with a differential electrode; an ion repulsion electrode is arranged below the vacuum ultraviolet lamp, the ion repulsion electrode is arranged in parallel with the differential electrode, the ion repulsion electrode and the differential electrode are connected through insulating columns, the insulating columns are at least 3 and are perpendicular to the differential electrode, a direct current transmission electrode group is arranged on the inner side of the insulating columns, a tubular membrane is arranged on the outer side of the insulating columns, and the tubular membrane is arranged in position correspondence with the direct current transmission motor group; and an ion funnel device is arranged below the direct current transmission electrode group. The application proposes a membrane sample injection ion funnel ionization source based on vacuum ultraviolet photoionization technology, and combines membrane sample injection enrichment technology and ion funnel ion focusing technology, so that the detection sensitivity of the instrument is greatly improved.

Description

Technical Field

[0001] This invention relates to a membrane-injection ion funnel ionization source device, belonging to the technical field of mass spectrometry analyzers. Background Technology

[0002] Membrane-guided mass spectrometry (MBS) separates analytes from the liquid or gas phase using a semi-permeable membrane, allowing for direct detection in a mass spectrometer without chromatographic separation. MBS enables the direct determination of trace VOCs in water or air without interference from acids, alkalis, metals, ions, suspended solids, or high-molecular-weight organic compounds. MBS is simple in structure, requires no complex sample pretreatment procedures, can enrich samples, has a short response time, is fast, and has low analysis cost per sample, meeting the needs of online analysis. Furthermore, because it requires no additional solvent, it is suitable for portable instruments and can be easily connected to various high-sensitivity detectors for automated operation and online detection, making it applicable to long-term online analysis processes. Photoionization mass spectrometry (PMS) directly obtains the molecular weight information of the sample, offering fast analysis speed and strong qualitative capabilities, making it suitable for rapid online detection of volatile and semi-volatile organic compounds.

[0003] Li Haiyang et al. invented an ultraviolet photochemical ionization source based on an ion funnel (application number 201611019684.5). The specific structure includes an ionization source cavity, a vacuum ultraviolet lamp, an excitation electrode, a reagent gas inlet tube, a repulsion electrode, a sample gas inlet tube, an ion funnel, and a differential electrode. The advantage is that the ionization source utilizes the superior focusing performance of the ion funnel under moderate gas pressure, improving the sufficiency of the reaction between reagent ions and sample molecules, as well as the transport efficiency of sample ions. This enhances the ionization efficiency of the vacuum ultraviolet photochemical ionization source and significantly improves the instrument's sensitivity.

[0004] Li Haiyang et al. invented a vacuum ultraviolet photoionization source for high-throughput gas sample analysis (patent number ZL201010567335.3). Specifically, it is a vacuum ultraviolet photoionization source for high-throughput gas sample analysis, including an ionization source cavity and a vacuum ultraviolet light source. A gas inlet is provided at the top of the ionization source cavity, through which the gas sample enters the interior of the ionization source cavity. Inside the ionization source cavity, ion extraction electrodes, an ion funnel, and a differential interface plate are arranged sequentially along the gas sample flow direction, spaced apart, coaxial, and parallel. The vacuum ultraviolet light source is located on the side wall of the ionization source cavity, and the vacuum ultraviolet light emitted by the vacuum ultraviolet light source is parallel to the plates of the ion extraction electrodes and passes through the areas between the plates to enter the through-hole area of ​​the ion extraction electrodes.

[0005] Existing devices have low detection sensitivity, are limited to gas detection, and have a single detection target; further improvements in detection sensitivity are possible. Summary of the Invention

[0006] To address the above shortcomings, the present invention provides a membrane-injected ion funnel ionization source device. The device has high detection sensitivity and can perform not only gas detection but also highly sensitive detection of volatile organic compounds in liquid samples.

[0007] The device used to solve the technical problem of this invention includes an ionization source cavity, a vacuum ultraviolet lamp at the top of the ionization source cavity, and a differential electrode at the bottom of the ionization source cavity. Below the vacuum ultraviolet lamp is an ion repulsion electrode, which is arranged parallel to the differential electrode and connected to it by insulating columns. There are at least three insulating columns perpendicular to the differential electrode. A DC transmission electrode assembly is located inside each insulating column, and a tubular membrane is located outside each insulating column, with the tubular membrane corresponding to the position of the DC transmission electrode assembly. An ion funnel device is located below the DC transmission electrode assembly.

[0008] The ion repulsion electrode, the DC transmission electrode group, and the differential electrode are all flat plate structures with a circular through hole in the middle, and all the flat plate structures are arranged in parallel, with the center of all the circular through holes on the same central axis.

[0009] A mass analyzer is provided on the outer side of the bottom of the differential electrode; the ionization source cavity is a vacuum environment and is provided with a sample inlet tube and an outlet tube.

[0010] Preferably, the number of insulating posts is 3-6. The insulating posts are made of polyetheretherketone (PEEK).

[0011] Optionally, the ionization source cavity is provided with a sample inlet tube on one side, one end of which is connected to the sample, and the other end of which is connected to the tubular membrane near the ion repulsion electrode. A heating device is provided on the outside of the sample inlet tube. Below the sample inlet tube, an outflow tube is provided, one end of which is connected to the tubular membrane near the ion funnel device, and the other end of which is connected to the waste liquid recovery bottle located on the outside of the ionization source cavity. The other side of the ionization source cavity is connected to a mechanical vacuum pump, and a gas valve is provided between the mechanical vacuum pump and the ionization source cavity. The ionization source cavity is also provided with a vacuum gauge.

[0012] Optionally, the DC transmission electrode group is formed by several metal plates with circular apertures in the middle arranged vertically at equal intervals in parallel, and the circular apertures gradually increase in size from the end of the vacuum ultraviolet lamp.

[0013] Optionally, the ion funnel device is composed of several annular metal electrodes with the same outer diameter but different inner diameters, arranged vertically at equal intervals in parallel. The metal electrodes are arranged from top to bottom with their inner diameters decreasing sequentially. The axial cross-section of the ion funnel device is an inverted trapezoid, and the largest inner diameter of the metal electrode is the same as the aperture of the metal plate in the DC transmission motor unit.

[0014] Preferably, the number of metal electrodes is 2-200, and the diameter of the circular through hole of the metal electrode is 0.5-50mm.

[0015] Optionally, the ion repulsion electrode, the DC transmission electrode group, the ion funnel device, and the differential electrode are sequentially loaded with different axial voltages in descending order of voltage, forming an ion excitation electric field of 2 to 500 V / cm in the axial direction of the tubular membrane region; the frequency applied to the ion funnel device is 0.5 to 3 MHz, and the peak value is 10 to 600 V.

[0016] Optionally, the tubular membrane is made of polydimethylsiloxane (PDMS), and the thickness of the tubular membrane is 25-300 μm, with a winding length of 7-200 cm.

[0017] Optionally, the optical axis of the emitted light from the vacuum ultraviolet lamp is coaxial with the ion repulsion electrode, the DC transmission electrode group, the ion funnel device, and the central through hole of the differential electrode.

[0018] Optionally, the mass analyzer is selected from one of a time-of-flight mass analyzer, a quadrupole mass analyzer, and an ion trap mass analyzer.

[0019] Optionally, the gas valve is a flow-adjustable vacuum valve, selected from a vacuum baffle valve, a vacuum needle valve, and a vacuum butterfly valve. The vacuum ultraviolet lamp is selected from a gas discharge lamp light source, a laser light source, and a synchrotron radiation light source.

[0020] Principle: Gas or liquid samples flow through a PDMS tubular membrane via a sample inlet tube. Volatile organic compounds selectively permeate the PDMS membrane and enter the ionization source chamber. A vacuum UV lamp irradiates the sample molecules, directly causing photoionization. Under the electric field of the ion repulsion electrode and DC transmission electrode assembly, the photoionized ions move forward. Under the influence of the ion funnel's radio frequency field, the sample ions are gradually focused to the center of the ion funnel, resulting in high transmission efficiency. Simultaneously, the enrichment effect of membrane introduction and the focusing effect of the ion funnel significantly improve the instrument's sensitivity.

[0021] Beneficial effects: Based on vacuum ultraviolet photoionization technology, this invention proposes a membrane-introduced ion funnel ionization source, which combines membrane-introduced enrichment technology with ion funnel ion focusing technology, greatly improving the detection sensitivity of the instrument. Moreover, it can not only perform gas detection, but also achieve highly sensitive detection of volatile organic compounds in liquid samples. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the device structure involved in the present invention.

[0023] As shown in the figure, 1. Ionization source chamber, 2. Vacuum ultraviolet lamp, 3. Ion repulsion electrode, 4. Insulating column, 5. DC transmission electrode assembly, 6. Ion funnel device, 7. Differential electrode, 8. Tubular membrane, 9. Heating device, 10. Sample inlet tube, 11. Outlet tube, 12. Waste liquid recovery bottle, 13. Gas valve, 14. Mechanical vacuum pump, 15. Vacuum gauge, 16. Mass analyzer. Detailed Implementation

[0024] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0025] Unless otherwise specified, all components in the embodiments of this application were purchased commercially.

[0026] Example 1

[0027] The device in this embodiment includes an ionization source cavity 1, a vacuum ultraviolet lamp 2 at the top of the ionization source cavity 1, and a differential electrode 7 at the bottom of the ionization source cavity 1. An ion repulsion electrode 3 is located below the vacuum ultraviolet lamp 2, and the ion repulsion electrode 3 is arranged parallel to the differential electrode 7. The ion repulsion electrode 3 and the differential electrode 7 are connected by an insulating column 4, which has six columns and is perpendicular to the differential electrode 7. A DC transmission electrode assembly 5 is located inside the insulating column 4, and a tubular membrane 8 is located outside the insulating column 4, with the tubular membrane 8 corresponding to the position of the DC transmission electrode assembly 5. An ion funnel device 6 is located below the DC transmission electrode assembly 5.

[0028] The ion repulsion electrode 3, the DC transmission electrode group 5, and the differential electrode 7 are all flat plate structures with a circular through hole in the middle, and all the flat plate structures are arranged in parallel, with the center of all the circular through holes on the same central axis.

[0029] The differential electrode 7 has a mass analyzer 16 on its outer bottom; the ionization source cavity 1 is a vacuum environment, and the ionization source cavity 1 is equipped with a sample inlet tube 10 and an outlet tube 11.

[0030] The ionization source cavity 1 is provided with a sample inlet tube 10 on one side. One end of the sample inlet tube 10 is connected to the sample, and the other end of the sample inlet tube 10 is connected to the tubular membrane 8 near the ion repulsion electrode 3. A heating device 9 is provided on the outside of the sample inlet tube 10. Below the sample inlet tube 10, there is an outlet tube 11. One end of the outlet tube 11 is connected to the tubular membrane 8 near the ion funnel device 6, and the other end of the outlet tube 11 is connected to the waste liquid recovery bottle 12 located on the outside of the ionization source cavity 11. The other side of the ionization source cavity 1 is connected to a mechanical vacuum pump 14. A gas valve 13 is provided between the mechanical vacuum pump 14 and the ionization source cavity 1. The ionization source cavity 1 is also provided with a vacuum gauge 15.

[0031] The DC transmission electrode group 5 is composed of several metal plates with circular apertures in the middle, arranged vertically at equal intervals in parallel. The circular apertures gradually increase in size from the end of the vacuum ultraviolet lamp 2.

[0032] The ion funnel device 6 is composed of several annular metal electrodes with the same outer diameter but different inner diameters, arranged vertically at equal intervals in parallel. The metal electrodes are arranged from top to bottom with their inner diameters decreasing sequentially. The axial cross-section of the ion funnel device 6 is an inverted trapezoid. The largest inner diameter of the metal electrode is the same as the aperture of the metal plate in the DC transmission motor unit 5.

[0033] The number of metal electrodes is 2-200, and the diameter of the circular through hole of the metal electrode is 0.5-50mm.

[0034] The ion repulsion electrode 3, the DC transmission electrode group 5, the ion funnel device 6, and the differential electrode 7 are sequentially applied with different axial voltages in descending order of voltage, forming an ion excitation electric field of 2 to 500 V / cm in the axial direction of the tubular membrane 8 region; the frequency applied to the ion funnel device 6 is 0.5 to 3 MHz, and the peak value is 10 to 600 V.

[0035] The tubular membrane 8 is made of polydimethylsiloxane (PDMS), and its thickness is 25-300 μm, with a winding length of 7-200 cm.

[0036] The optical axis of the light emitted from the vacuum ultraviolet lamp 2 is coaxial with the ion repulsion electrode 3, the DC transmission electrode group 5, the ion funnel device 6, and the central through hole of the differential electrode 7.

[0037] The mass analyzer 16 is selected from one of the following: time-of-flight mass analyzer, quadrupole mass analyzer, and ion trap mass analyzer.

[0038] The gas valve 13 is a vacuum butterfly valve. The vacuum ultraviolet lamp 2 is a synchrotron radiation source.

[0039] Example 2

[0040] The device in this embodiment includes an ionization source cavity 1 and a vacuum ultraviolet lamp 2. An air extraction port and a through hole are opened on the side wall of the ionization source cavity 1, and the through hole is sealed and connected to the vacuum gauge 15.

[0041] The vacuum ultraviolet lamp 2 is sealed and placed on the top of the ionization source cavity 1. An ion repulsion electrode 3, a DC transmission electrode group 5, an ion funnel device 6 and a differential electrode 7 are arranged sequentially along the light emission direction of the vacuum ultraviolet lamp 2.

[0042] The ion repulsion electrode 3, the DC transmission electrode group 5, and the differential electrode 7 are all flat plate structures with a circular through hole in the middle; the electrode plates of the ion funnel device 6 are all annular flat plates with a circular through hole in the middle of the annulus.

[0043] The optical axis of the light emitted from the vacuum ultraviolet lamp 2 is coaxial with the through hole in the middle of the ion repulsion electrode 3, the DC transmission electrode group 5, the ion funnel device 6, and the differential electrode 7.

[0044] The DC transmission electrode group 5 consists of one or more electrode pieces, which are embedded in the insulating and fixing insulating post 4. The insulating post 4 is cylindrical and fixed on the repulsion electrode 3, and there are three such posts.

[0045] A polydimethylsiloxane (PDMS) tubular film 8 is wound around the insulating column 4 that fixes the DC transmission electrode assembly 5; a sample (either a gaseous or liquid sample) injection tube 10 is located near the repulsion electrode 3, and a heating device 9 is provided on the injection tube 10 before it enters the ionization source cavity 1; a waste liquid or waste gas outflow tube 11 is located near the ion funnel device 6, and a waste liquid recovery bottle or waste gas treatment bottle 12 is provided at the tail of the outflow tube 11.

[0046] The ion repulsion electrode 3 and the DC transmission electrode group 5 are both placed in parallel, equally spaced, and coaxially with through holes; the electrode of the ion funnel device 6 is an annular plate with a circular through hole in the middle of the annulus, and two or more electrode plates are placed in parallel, equally spaced, and coaxially with through holes.

[0047] The ion funnel device has 6 metal electrodes, the inner diameter of the through hole gradually decreases, the axial section is an inverted trapezoid, the number of electrodes is 2-200, and the diameter of the circular through hole of the electrode is 0.5-50mm.

[0048] Different axial voltages are sequentially applied to the ion repulsion electrode 3, the DC transmission electrode group 5, the ion funnel device 6, and the differential electrode 7 in descending order of voltage, thereby forming an ion excitation electric field with a magnitude of 2 to 500 V / cm in the axial direction of the PDMS tubular film 8 region; the frequency applied to the ion funnel device 6 is 0.5 to 3 MHz, and the peak-to-peak value is 10 to 600 V.

[0049] The PDMS tubular film has a thickness of 25–300 μm and a winding length of 7–200 cm.

[0050] The differential electrode 7 is provided with a differential interface hole, which is connected to the mass analyzer 16; the mass analyzer is a time-of-flight mass analyzer, a quadrupole mass analyzer, or an ion trap mass analyzer.

[0051] A gas outlet is provided on the side wall of the ionization source cavity 1. The gas outlet is connected to a gas valve 13 through a vacuum pipeline. The other end of the gas valve 13 is connected to a mechanical vacuum pump 14 through a vacuum pipeline.

[0052] The gas valve 13 is a vacuum valve with adjustable flow rate, such as a vacuum baffle valve, a vacuum needle valve, or a vacuum butterfly valve.

[0053] The vacuum ultraviolet lamp 2 is a gas discharge lamp light source, a laser light source, or a synchrotron radiation light source.

[0054] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A membrane-injected ion funnel ionization source device, characterized in that, The device includes an ionization source cavity (1), a vacuum ultraviolet lamp (2) at the top of the ionization source cavity (1), and a differential electrode (7) at the bottom of the ionization source cavity (1); an ion repulsion electrode (3) is provided below the vacuum ultraviolet lamp (2), the ion repulsion electrode (3) is arranged parallel to the differential electrode (7), the ion repulsion electrode (3) and the differential electrode (7) are connected by insulating columns (4), there are at least 3 insulating columns (4) and they are perpendicular to the differential electrode (7), a DC transmission electrode group (5) is provided inside the insulating column (4), and a tubular membrane (8) is provided outside the insulating column (4), the tubular membrane (8) is arranged in a position corresponding to the DC transmission electrode group (5); an ion funnel device (6) is provided below the DC transmission electrode group (5). The ion repulsion electrode (3), the DC transmission electrode group (5), and the differential electrode (7) are all flat plate structures with circular through holes in the middle, and all the flat plate structures are arranged in parallel, with the centers of all the circular through holes on the same central axis. The differential electrode (7) is provided with a mass analyzer (16) on the outer side of its bottom; the ionization source cavity (1) is a vacuum environment, and the ionization source cavity (1) is provided with a sample inlet tube (10) and an outlet tube (11).

2. The apparatus according to claim 1, characterized in that, The ionization source cavity (1) is provided with a sample inlet tube (10) on one side. One end of the sample inlet tube (10) is connected to the sample, and the other end of the sample inlet tube (10) is connected to the tubular membrane (8) near the ion repulsion electrode (3). A heating device (9) is provided on the outside of the sample inlet tube (10). An outlet tube (11) is provided below the sample inlet tube (10). One end of the outlet tube (11) is connected to the tubular membrane (8) near the ion funnel device (6), and the other end of the outlet tube (11) is connected to the waste liquid recovery bottle (12) located on the outside of the ionization source cavity (11). The other side of the ionization source cavity (1) is connected to a mechanical vacuum pump (14). A gas valve (13) is provided between the mechanical vacuum pump (14) and the ionization source cavity (1). The ionization source cavity (1) is also provided with a vacuum gauge (15).

3. The apparatus according to claim 1, characterized in that, The DC transmission electrode group (5) is formed by several metal plates with circular apertures in the middle arranged vertically at equal intervals in parallel. The circular apertures gradually increase in size from the end of the vacuum ultraviolet lamp (2).

4. The apparatus according to claim 3, characterized in that, The ion funnel device (6) is composed of several annular metal electrodes with the same outer diameter but different inner diameters, arranged vertically at equal intervals in parallel. The metal electrodes are arranged from top to bottom with their inner diameters decreasing sequentially. The axial cross section of the ion funnel device (6) is an inverted trapezoid. The largest inner diameter of the metal electrode is the same as the aperture of the metal plate in the DC transmission electrode group (5).

5. The apparatus according to claim 3, characterized in that, The number of metal electrodes is 2-200, and the diameter of the circular through hole of the metal electrode is 0.5-50 mm.

6. The apparatus according to claim 1, characterized in that, The ion repulsion electrode (3), the DC transmission electrode group (5), the ion funnel device (6), and the differential electrode (7) are sequentially loaded with different axial voltages in order from high to low voltage, and an ion excitation electric field of 2~500 V / cm is formed in the axial direction of the tubular membrane (8); the frequency applied to the ion funnel device (6) is 0.5~3 MHz, and the peak value is 10~600 V.

7. The apparatus according to claim 1, characterized in that, The tubular membrane (8) is made of polydimethylsiloxane, and the thickness of the tubular membrane (8) is 25~300 μm, and the winding length is 7~200 cm.

8. The apparatus according to claim 1, characterized in that, The optical axis of the emitted light from the vacuum ultraviolet lamp (2) is coaxial with the ion repulsion electrode (3), the DC transmission electrode group (5), the ion funnel device (6), and the central through hole of the differential electrode (7).

9. The apparatus according to claim 1, characterized in that, The mass analyzer (16) is selected from one of the time-of-flight mass analyzers, quadrupole mass analyzers, and ion trap mass analyzers.

10. The apparatus according to claim 2, characterized in that, The gas valve (13) is selected from one of the following: vacuum baffle valve, vacuum needle valve, and vacuum butterfly valve; the vacuum ultraviolet lamp (2) is selected from one of the following: gas discharge lamp light source, laser light source, and synchrotron radiation light source.

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