Orthogonal electrochemical mass spectrometry device

Abstract

The invention relates to the technical field of mass spectrum analyzers, in particular to an orthogonal electrochemical mass spectrum device. Comprising a photoionization system, an electron ionization system and an electrochemical reaction tank, the electrochemical reaction tank is sequentially connected with the photoionization system and the electron ionization system through a vacuum sampling pipe, and the photoionization system ionizes volatile organic compound gas generated in the electrochemical reaction tank to obtain a soft ionization spectrogram of the volatile organic compound gas; the electron ionization system is used for ionizing inorganic components generated in the electrochemical reaction tank to obtain an inorganic component mass spectrum. The photoionization source and the electron ionization source are ingeniously and orthogonally combined, soft ionization of volatile organic compounds and effective ionization of high-ionization-energy inorganic compounds in the electrochemical process can be achieved at the same time, and therefore the real-time concentration change trend of the volatile organic compounds and inorganic compounds is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of mass spectrometers, and in particular, to an orthogonal electrochemical mass spectrometry device. Background Art

[0002] The analysis of electrochemical processes is an important way to study the mechanism of electrochemical reactions, and it has important guiding significance for the development of organic electrosynthesis methods, the design of electrochemical catalysts, etc. Traditional electroanalysis methods, such as potentiostatic method, voltammetry, coulometry, etc., can only monitor electrical parameters such as current and potential during electrochemical reactions, but cannot provide molecular information during the reaction process. In recent years, the emerging in-situ electrochemical mass spectrometry analysis technology has high sensitivity, good specificity, and the functions of simultaneous analysis of multiple components and identification of unknown structure, and has become a powerful means for monitoring electrochemical reaction products and capturing and identifying intermediates. However, almost all existing electrochemical mass spectrometry gases use electron impact ionization mass spectrometry (EI-MS). Although this type of mass spectrometry has a high ionization efficiency, it has serious fragmentation problems, and can only analyze inorganic gases in some simple electrochemical systems. There are problems of spectral peak overlap for volatile organic compounds (VOCs) in complex gas production components, and it is difficult to perform qualitative and quantitative analysis.

[0003] Through patent and paper retrieval, the patents related to electrochemical mass spectrometry and ionization retrieved are as follows: 1. A device and its usage method for electrochemical-mass spectrometry coupling, applied and disclosed by Harbin Institute of Technology (Weihai) on October 19, 2018, includes a mass spectrometer and an electrochemical reaction device. The electrochemical reaction platform is a carrier with at least one sharp corner, and one sharp corner of the carrier is set as the sample corner; the electrochemical electrode combination controls the voltage for electrochemical reaction and the ionization spray voltage of the sample solution through a power supply workstation, so that the sample solution to be measured at the sample corner undergoes an electrochemical reaction and generates electrospray ionization, and the ions of the electrospray enter the mass spectrometry inlet. This method is mainly used for liquid components and cannot be used for gas components. 2. Shanghai Zero Dew Instrument Equipment Co., Ltd. applied and disclosed an electrochemical mass spectrometry coupling instrument on July 27, 2018, including a carrier gas injection system, an electrochemical cell, an electrochemical workstation, and a mass spectrometer; the mass spectrometer has a multi-channel inlet, an electron ionization source, and a detector, and can record and display in real time the components, contents of the products of each channel and their changes over time, and provide mass spectrometry analysis data of the reaction products in the electrochemical cell. However, its EI source has serious fragmentation and cannot meet the detection requirements of volatile organic compounds during electrochemical reactions. Therefore, there is still a need to develop an electrochemical mass spectrometry method that can simultaneously analyze inorganic gases and volatile organic compounds in complex components. Summary of the Invention

[0004] Aiming at the above problems, the purpose of the present invention is to provide an orthogonal electrochemical mass spectrometry device to achieve simultaneous analysis of inorganic and organic gases during the electrochemical process.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides an orthogonal electrochemistry mass spectrometry device, including a photoionization system, an electron ionization system, and an electrochemical reaction cell. The electrochemical reaction cell is sequentially connected to the photoionization system and the electron ionization system through a vacuum sampling tube. The photoionization system ionizes the volatile organic compound gas generated in the electrochemical reaction cell to obtain a soft ionization spectrum of the volatile organic compound gas; the electron ionization system is used to ionize the inorganic components generated in the electrochemical reaction cell to obtain a mass spectrum of the inorganic components.

[0007] The photoionization system includes a photoionization cavity, a vacuum ultraviolet light source, a converging light window, a photoionization repulsion electrode, a photoionization ion introduction electrode, and a first mass spectrometer. The converging light window and the first mass spectrometer are respectively arranged on both sides of the photoionization cavity along the x direction. The photoionization repulsion electrode and the photoionization ion introduction electrode are arranged in the photoionization cavity along the x direction, and the vacuum ultraviolet light source is arranged outside the converging light window;

[0008] The vacuum ultraviolet light generated by the vacuum ultraviolet light source enters the photoionization cavity through the converging light window and ionizes the volatile organic compound gas entering the photoionization cavity. The ions generated after ionization enter the first mass spectrometer along the x direction under the action of the photoionization repulsion electrode and the photoionization ion introduction electrode for analysis.

[0009] Both the photoionization repulsion electrode and the photoionization ion introduction electrode are flat structures with cylindrical through holes in the middle, and the center of the vacuum ultraviolet light source, the central axis of the converging light window, the central hole of the photoionization repulsion electrode, and the central hole of the photoionization ion introduction electrode are coaxially placed.

[0010] The vacuum ultraviolet light source is a gas discharge light source, a laser light source, or a synchrotron radiation light source; the converging light window is a magnesium fluoride or lithium fluoride light window.

[0011] The electron ionization system includes an electron ionization cavity, an electron ionization ion introduction electrode, a second mass spectrometer, an electron ionization source, and an electron ionization repulsion electrode. The two sides of the electron ionization cavity along the y direction are respectively connected to the photoionization cavity and the second mass spectrometer. The electron ionization repulsion electrode, the electron ionization source, and the electron ionization ion introduction electrode are sequentially arranged in the electron ionization cavity along the y direction.

[0012] The gas generated in the electrochemical reaction cell enters the electron ionization cavity along the Y direction under the action of a vacuum pressure difference and ionizes the inorganic components under the action of the electron ionization source. The ions generated enter the second mass spectrometer for analysis under the action of the electron ionization repulsion electrode and the electron ionization ion introduction electrode.

[0013] The electron ionization repeller electrode and the electron ionization ion introduction electrode are both flat plate structures with a cylindrical through hole in the middle, and the axis of the vacuum sampling tube, the central hole of the electron ionization repeller electrode and the central hole of the electron ionization ion introduction electrode are coaxially arranged.

[0014] The air pressure in the photoionization chamber is 0.1-100 Pa; the air pressure in the electron ionization chamber is 0.001-0.0001 Pa.

[0015] The first mass spectrometer and the second mass spectrometer are any two of a quadrupole mass spectrometer, a time-of-flight mass spectrometer, a magnetic mass spectrometer, an ion trap mass spectrometer and an orbital trap mass spectrometer.

[0016] A filter membrane is provided at the bottom of the electrochemical reaction cell, and the upper end of the filter membrane contacts the liquid in the electrochemical reaction cell. The gas in the liquid can enter the photoionization cavity along the y direction under the vacuum action of the vacuum sampling tube.

[0017] The advantages and beneficial effects of the present invention are as follows: the orthogonal electrochemical mass spectrometer provided by the present invention, through reasonable design, cleverly orthogonally combines the photoionization source and the electron ionization source, can simultaneously realize the soft ionization of volatile organic compounds in the electrochemical process, and the effective ionization of high ionization energy inorganic compounds, thereby obtaining the real-time concentration change trend of volatile organic compounds and inorganic compounds. The present invention can realize a more comprehensive analysis of the gas components in the electrochemical process, and is expected to become a powerful tool for studying the mechanism of the electrochemical reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings further illustrate the present invention, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0019] Figure 1 It is a structural schematic diagram of an orthogonal electrochemical mass spectrometry device of the present invention.

[0020] In the figure: 1-electrochemical reaction cell, 2-filter membrane, 3-vacuum sampling tube, 4-photoionization chamber, 5-vacuum ultraviolet light source, 6-converging light window, 7-photoionization repeller electrode, 8-electron ionization chamber, 9-electron ionization ion introduction electrode, 10-second mass spectrometer, 11-electron ionization source, 12-electron ionization repeller electrode, 13-first mass spectrometer, 14-photoionization ion introduction electrode. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. The description of at least one exemplary embodiment is actually illustrative only and in no way restricts the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0023] It should be noted that the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly dictates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of the stated features, steps, operations, devices, components, and / or combinations thereof.

[0024] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the authorized specification. In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0025] In the description of the present invention, it should be understood that orientation terms such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. generally indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus cannot be construed as limiting the scope of protection of the present invention. The orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0026] As Figure 1As shown in the figure, the present invention provides an orthogonal electrochemical mass spectrometry device, including a photoionization system, an electron ionization system, and an electrochemical reaction cell 1. The electrochemical reaction cell 1 is sequentially connected to the photoionization system and the electron ionization system through a vacuum sampling tube 3. The photoionization system ionizes the volatile organic compound gas generated in the electrochemical reaction cell 1 to obtain a soft ionization spectrum of the volatile organic compound gas; the electron ionization system is used to ionize the inorganic components generated in the electrochemical reaction cell 1 to obtain a mass spectrum of the inorganic components.

[0027] In the embodiment of the present invention, the left direction is taken as the X direction and the downward direction is taken as the Y direction, as Figure 1 shown; the photoionization system includes a photoionization cavity 4, a vacuum ultraviolet light source 5, a converging light window 6, a photoionization repulsion electrode 7, a photoionization ion introduction electrode 14, and a first mass spectrometer 13. The converging light window 6 and the first mass spectrometer 13 are respectively arranged on both sides of the photoionization cavity 4 along the x direction. The photoionization repulsion electrode 7 and the photoionization ion introduction electrode 14 are arranged in the photoionization cavity 4 along the x direction, and the vacuum ultraviolet light source 5 is arranged outside the converging light window 6. The vacuum ultraviolet light generated by the vacuum ultraviolet light source 5 enters the photoionization cavity 4 through the converging light window 6 and ionizes the volatile organic compound gas entering the photoionization cavity 4. The ions generated after ionization enter the first mass spectrometer 13 along the x direction under the action of the photoionization repulsion electrode 7 and the photoionization ion introduction electrode 14 for analysis.

[0028] Furthermore, both the photoionization repulsion electrode 7 and the photoionization ion introduction electrode 14 are flat plate structures with a cylindrical through hole in the middle, and the center of the vacuum ultraviolet light source 5, the central axis of the converging light window 6, the central hole of the photoionization repulsion electrode 7, and the central hole of the photoionization ion introduction electrode 14 are coaxially placed. The converging light window 6 is embedded in the side wall of the photoionization cavity 4 for introducing the light generated by the vacuum ultraviolet light source 5; the photoionization repulsion electrode 7 and the photoionization ion introduction electrode 14 are respectively located on both sides of the axis of the vacuum sampling tube 3.

[0029] In this embodiment, the vacuum ultraviolet light source 5 is a gas discharge light source, a laser light source, or a synchrotron radiation light source; the converging light window 6 is a magnesium fluoride or lithium fluoride light window. Preferably, the vacuum ultraviolet light source 5 is a Kr discharge lamp source, which has the advantages of small volume, low power consumption, and high cost performance. The photons with an energy of 10.6 eV generated by it can meet the measurement of most volatile organic compounds; the converging light window 6 uses a magnesium fluoride light window.

[0030] In an embodiment of the present invention, the electron ionization system includes an electron ionization chamber 8, an electron ionization ion introduction electrode 9, a second mass spectrometer 10, an electron ionization source 11, and an electron ionization repulsion electrode 12. The two sides of the electron ionization chamber 8 along the y direction are respectively connected to the photoionization chamber 4 and the second mass spectrometer 10. The electron ionization repulsion electrode 12, the electron ionization source 11, and the electron ionization ion introduction electrode 9 are sequentially arranged in the electron ionization chamber 8 along the y direction. The gas generated in the electrochemical reaction cell 1 enters the electron ionization chamber 8 along the Y direction under the action of the vacuum pressure difference, and the inorganic components are ionized under the action of the electron ionization source 11. The generated ions enter the second mass spectrometer 10 for analysis under the action of the electron ionization repulsion electrode 12 and the electron ionization ion introduction electrode 9.

[0031] Furthermore, both the electron ionization repulsion electrode 12 and the electron ionization ion introduction electrode 9 are flat plate structures with cylindrical through holes in the middle, and the axis of the vacuum sampling tube 3, the central hole of the electron ionization repulsion electrode 12, and the central hole of the electron ionization ion introduction electrode 9 are coaxially placed.

[0032] In this embodiment, the air pressure in the photoionization chamber 4 is 0.1 - 100 Pa; the air pressure in the electron ionization chamber 8 is 0.001 - 0.0001 Pa. Preferably, the air pressure in the photoionization chamber 4 is 10 Pa, which not only has sufficient fractional density but also can avoid complex molecular ion reactions; the air pressure in the electron ionization chamber 8 is 0.001 Pa. Under the premise of meeting the operating pressure of the EI source, the molecular number density is increased as much as possible to improve the sensitivity. The first mass spectrometer 13 and the second mass spectrometer 10 are any two of a quadrupole mass spectrometer, a time-of-flight mass spectrometer, a magnetic mass spectrometer, an ion trap mass spectrometer, and an orbitrap mass spectrometer. Preferably, the first mass spectrometer 13 selects a time-of-flight mass spectrometer, which has a high analysis speed and resolution; the second mass spectrometer 10 selects a quadrupole mass spectrometer for measuring inorganic small molecules and does not require high resolution.

[0033] In an embodiment of the present invention, a filter membrane 2 is provided at the bottom of the electrochemical reaction cell 1. The upper end of the filter membrane 2 contacts the liquid in the electrochemical reaction cell 1. The gas in the liquid can enter the photoionization chamber 4 along the y direction under the vacuum action of the vacuum sampling tube 3. Preferably, the vacuum sampling tube 3 is a hollow circular tube.

[0034] The working principle of an orthogonal electrochemical mass spectrometry device provided by the present invention is:

[0035] During operation, the gas generated in the electrochemical reaction cell 1 enters the photoionization cavity 4 through the filter membrane 2; the vacuum ultraviolet light generated by the vacuum ultraviolet light source 5 enters the photoionization cavity 4 through the focusing window 6 and ionizes the volatile organic compound (VOCs) gas with low ionization energy generated in the electrochemical reaction cell 1, and the ions generated after ionization enter the first mass spectrometer 13 along the x direction for analysis under the action of the photoionization repeller electrode 7 and the photoionization ion introduction electrode 14, so as to obtain a clean VOCs soft ionization spectrum; at the same time, the gas generated in the electrochemical reaction cell 1 enters the electron ionization cavity 8 along the y direction under the action of the vacuum pressure difference, and ionizes the inorganic components with high ionization energy under the action of the electron ionization source 11, and the generated ions enter the second mass spectrometer 10 for analysis under the action of the electron ionization repeller electrode 12 and the electron ionization ion introduction electrode 9, so as to obtain an inorganic component mass spectrum; thereby realizing the simultaneous in-situ detection of volatile organic components and inorganic components in the electrochemical reaction process.

[0036] The present invention, through reasonable design, cleverly orthogonally combines the photoionization source and the electron ionization source, and can simultaneously realize the soft ionization of volatile organic compounds in the electrochemical process, and the effective ionization of high ionization energy inorganic compounds, thereby obtaining the real-time concentration change trend of volatile organic compounds and inorganic compounds. The present invention can realize a more comprehensive analysis of the gas components in the electrochemical process, and is expected to become a powerful tool for studying the mechanism of the electrochemical reaction process.

[0037] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific embodiments of the present invention without creative work, and these equivalent variations or substitutions are all included in the scope defined by the claims of this application.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An orthogonal electrochemical mass spectrometry device, characterized in that, it includes a photoionization system, an electron ionization system, and an electrochemical reaction cell (1). The electrochemical reaction cell (1) is sequentially connected to the photoionization system and the electron ionization system through a vacuum sampling tube (3). The photoionization system ionizes the volatile organic compound gas generated in the electrochemical reaction cell (1) to obtain a soft ionization spectrum of the volatile organic compound gas; the electron ionization system is used to ionize the inorganic components generated in the electrochemical reaction cell (1) to obtain a mass spectrum of the inorganic components.

2. The orthogonal electrochemical mass spectrometry device according to claim 1, characterized in that, the photoionization system includes a photoionization cavity (4), a vacuum ultraviolet light source (5), a converging light window (6), a photoionization repulsion electrode (7), a photoionization ion introduction electrode (14), and a first mass spectrometer (13). The converging light window (6) and the first mass spectrometer (13) are respectively arranged on both sides of the photoionization cavity (4) along the x direction. The photoionization repulsion electrode (7) and the photoionization ion introduction electrode (14) are arranged in the photoionization cavity (4) along the x direction. The vacuum ultraviolet light source (5) is arranged outside the converging light window (6); the vacuum ultraviolet light generated by the vacuum ultraviolet light source (5) enters the photoionization cavity (4) through the converging light window (6) and ionizes the volatile organic compound gas entering the photoionization cavity (4). The ions generated after ionization enter the first mass spectrometer (13) along the x direction under the action of the photoionization repulsion electrode (7) and the photoionization ion introduction electrode (14) for analysis.

3. The orthogonal electrochemical mass spectrometry device according to claim 2, characterized in that, both the photoionization repulsion electrode (7) and the photoionization ion introduction electrode (14) are flat structures with a cylindrical through hole in the middle, and the center of the vacuum ultraviolet light source (5), the central axis of the converging light window (6), the central hole of the photoionization repulsion electrode (7), and the central hole of the photoionization ion introduction electrode (14) are coaxially placed.

4. The orthogonal electrochemical mass spectrometry device according to claim 2, characterized in that, the vacuum ultraviolet light source (5) is a gas discharge light source, a laser light source, or a synchrotron radiation light source; the converging light window (6) is a magnesium fluoride or lithium fluoride light window.

5. The orthogonal electrochemical mass spectrometry device according to claim 2, characterized in that, the electron ionization system includes an electron ionization cavity (8), an electron ionization ion introduction electrode (9), a second mass spectrometer (10), an electron ionization source (11), and an electron ionization repulsion electrode (12). The two sides of the electron ionization cavity (8) along the y direction are respectively connected to the photoionization cavity (4) and the second mass spectrometer (10). The electron ionization repulsion electrode (12), the electron ionization source (11), and the electron ionization ion introduction electrode (9) are sequentially arranged in the electron ionization cavity (8) along the y direction. The gas generated in the electro-chemical reaction cell (1) enters the electron ionization cavity (8) along the Y direction under the action of the vacuum pressure difference, and the inorganic components are ionized under the action of the electron ionization source (11). The generated ions enter the second mass spectrometer (10) for analysis under the action of the electron ionization repulsion electrode (12) and the electron ionization ion introduction electrode (9).

6. The orthogonal electro-chemical mass spectrometry device according to claim 5, characterized in that, both the electron ionization repulsion electrode (12) and the electron ionization ion introduction electrode (9) are flat plate structures with cylindrical through holes in the middle, and the axis of the vacuum sampling tube (3), the central hole of the electron ionization repulsion electrode (12), and the central hole of the electron ionization ion introduction electrode (9) are coaxially arranged.

7. The orthogonal electro-chemical mass spectrometry device according to claim 5, characterized in that, the air pressure in the photoionization cavity (4) is 0.1 - 100 Pa; the air pressure in the electron ionization cavity (8) is 0.001 - 0.0001 Pa.

8. The orthogonal electro-chemical mass spectrometry device according to claim 5, characterized in that, the first mass spectrometer (13) and the second mass spectrometer (10) are any two of a quadrupole mass spectrometer, a time-of-flight mass spectrometer, a magnetic mass spectrometer, an ion trap mass spectrometer, and an orbitrap mass spectrometer.

9. The orthogonal electro-chemical mass spectrometry device according to claim 2, characterized in that, a filter membrane (2) is provided at the bottom of the electro-chemical reaction cell (1), the upper end of the filter membrane (2) contacts the liquid in the electro-chemical reaction cell (1), and the gas in the liquid can enter the photoionization cavity (4) along the y direction under the vacuum action of the vacuum sampling tube (3).

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