Mass spectrometer and gas phase ion source device

Abstract

The present invention relates to a mass spectrometer and a gas-phase ion source ionization device thereof in the field of mass spectrometer technology, comprising a first metal mesh, a second metal mesh and an ion source chamber; the first metal mesh and the second metal mesh are fixed in the ion source chamber in a parallel and spaced manner, the ion source chamber is provided with an injection port, a carrier gas inlet and an ion outlet, the injection port is located between the first metal mesh and the second metal mesh, the carrier gas inlet is located on the outside of the second metal mesh, and the ion outlet is located on the outside of the first metal mesh; the first metal mesh is loaded with a high level, the second metal mesh is loaded with a low level, a gaseous sample enters between the first metal mesh and the second metal mesh through the injection port, a change in the working gas pressure in the ion source chamber causes the first metal mesh to discharge to the second metal mesh, and ionized ions fly to the ion outlet under the auxiliary action of the voltage of the first metal mesh and the carrier gas. Compared with traditional gas-phase ionization sources, the present application has the advantages of being easy to miniaturize and simple in design, low in cost, free of consumables, and requiring no maintenance.

Description

Technical Field

[0001] The invention belongs to the technical field of gas sample ionization of a mass spectrometer, and in particular relates to a mass spectrometer and a gas phase ion source device thereof. Background Art

[0002] Mass spectrometry is a method of qualitative and quantitative analysis of substances by separating ions according to their mass-to-charge ratio using electric or magnetic fields. Instruments that perform mass spectrometry are collectively referred to as mass spectrometers. Mass spectrometers are a representative example of modern high-end analytical instruments. Due to their strong qualitative and quantitative capabilities, high sensitivity, and low detection limits, they are effective tools for trace detection of low-level substances. Currently, mass spectrometers are widely used in fields such as food safety, life sciences, medical testing, environmental monitoring, public safety, and aerospace. An increasing number of national and industry standards and analytical testing methods are based on mass spectrometry.

[0003] The ion source, as the core component of a mass spectrometer, is known as the "heart" of the instrument. In a mass spectrometer, the first step in analyzing the composition of a sample gas is ionization. Only then can the charged ions be mass analyzed to determine the sample's composition and concentration. The most commonly used gas-phase ion source in a mass spectrometer is the electron impact (EI) source, a "hard ionization" method. An EI source primarily consists of an ionization chamber (ion volume), a filament, an ion focusing lens, and a pair of magnetic poles. Its primary operating principle is that electrons with an energy of 70 eV are emitted from the filament, focused and guided by a magnetic field through the ionization chamber to the collector. Sample molecules entering the ionization chamber are ionized by the energetic electrons. Ions with higher internal energy spontaneously break apart upon collision with neutral molecules (such as He), producing numerous fragment ions. All ions are then focused and accelerated into an ion beam that enters the mass spectrometer. For most organic compounds, this hard ionization method of the EI source allows for the visualization of not only the parent ion but also numerous fragment ions, facilitating structural elucidation. Moreover, the standard spectral library uses an EI source to bombard known pure organic compounds at a collision energy of 70eV. After ionization, the molecular ions are further broken down to produce abundant fragment ions, forming a standard mass spectrum with rich "fingerprint" information. These standard mass spectra are stored as a standard spectral library.

[0004] However, there are some shortcomings in the actual application of electron bombardment sources in mass spectrometers. In the daily use of electron bombardment source mass spectrometers, the electron bombardment source, in principle, heats the filament with a constant high current and then emits electrons to ionize the sample molecules. Therefore, after the electron bombardment source has been used for a period of time, due to the long-term high-current heating of the filament and the corrosion of the sample gas, a layer of contaminants will adhere to the surface of the filament, the ionization efficiency of the filament will be significantly reduced, and the filament will need to be ultrasonically cleaned and maintained. The service life of the filament will also expire, and the filament will burn out and break. In order to alleviate the filament contamination during the use of the electron bombardment source, in actual applications, the ionization chamber of the electron bombardment source is generally heated and baked to volatilize the low-boiling point contaminants attached to the filament; at the same time, in order to reduce the frequency of filament replacement, a dual-filament structure has become the norm for sampling in electron bombardment sources. However, the filament itself is a consumable item, and its cost is relatively high. If imported filaments are used, it is even more expensive. Summary of the Invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a mass spectrometer and a gas phase ion source ionization device thereof.

[0006] According to the present invention, a gas phase ion source ionization device is provided, comprising a first metal mesh, a second metal mesh and an ionization source chamber;

[0007] The first metal mesh and the second metal mesh are fixed in parallel and spaced apart in the ionization source chamber. The ionization source chamber is provided with an injection port, a carrier gas inlet, and an ion outlet. The injection port is located between the first metal mesh and the second metal mesh, the carrier gas inlet is located outside the second metal mesh, and the ion outlet is located outside the first metal mesh.

[0008] The first metal mesh is loaded with a high level, and the second metal mesh is loaded with a low level. The gaseous sample enters between the first metal mesh and the second metal mesh through the sampling port. The change in the working gas pressure in the ionization source chamber causes the first metal mesh to discharge to the second metal mesh, and the gaseous sample located between the first metal mesh and the second metal mesh is ionized. The ionized ions fly toward the ion outlet under the assistance of the voltage of the first metal mesh and the carrier gas entering through the carrier gas inlet, and are led out of the ionization source chamber through the ion outlet and enter the next-level system.

[0009] In some embodiments, the first metal mesh and the second metal mesh are made of the same or different materials.

[0010] In some embodiments, the first metal mesh and the second metal mesh are made of stainless steel.

[0011] In some embodiments, the first metal mesh and the second metal mesh have the same or different shapes.

[0012] In some embodiments, the voltage difference applied between the first metal mesh and the second metal mesh is 2-3 kV, and the gap between the first metal mesh and the second metal mesh is 1.5-3 mm.

[0013] The present invention also provides a mass spectrometer, which adopts the gas phase ion source ionization device and also includes a sample introduction device, a carrier gas introduction device, an ion transmission device, a mass analyzer, an ion receiving device and a vacuum pump;

[0014] The sample introduction device delivers the gaseous sample to be tested between the first metal mesh and the second metal mesh through the sampling port, and the carrier gas introduction device inputs the carrier gas through the carrier gas inlet. The ionized ions fly toward the ion outlet under the assistance of the voltage of the first metal mesh and the carrier gas, and enter the ion transmission device through the ion outlet. They are then collimated and shaped by the ion transmission device and transmitted to the mass analyzer for analysis. After the analysis is completed, the ions enter the ion receiving device from the mass analyzer. The ion receiving device is used to form a mass spectrum, and the vacuum pump is used to achieve the vacuum environment required for the internal chamber of the mass spectrometer.

[0015] In some embodiments, the ion transmission device is an ion lens, an ion guide device, or a combination of an ion lens and an ion guide device.

[0016] In some embodiments, the mass analyzer is a quadrupole, ion trap, or time-of-flight mass spectrometer.

[0017] In some embodiments, the ion receiving device is a Faraday cage, an electron multiplier, or a microchannel plate.

[0018] In some embodiments, the carrier gas introduced by the carrier gas introduction device is an inert gas or an inert gas mixed with methane.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The gas-phase ion source ionization device provided in this application adopts a high-voltage metal mesh as the ionization source. Compared with traditional gas-phase ionization sources, it has the advantages of easy miniaturization, simple design, low cost, no consumables, and no maintenance. It greatly reduces the cost and can significantly extend the maintenance cycle, which is of great significance to the application field of miniaturized mass spectrometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0022] Figure 1Schematic diagram of the structure of the gas phase ion source ionization device of the present invention;

[0023] Figure 2 Schematic diagram of the structure of the metal mesh in the gas phase ion source ionization device of the present invention;

[0024] Figure 3 Schematic diagram of the structure of the mass spectrometer of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment provides a gas phase ion source ionization device, such as Figure 1-2 As shown, the ionization source chamber 3 includes an ionization source chamber 3 and a first metal mesh 1 and a second metal mesh 2 fixed in the ionization source chamber 3. The first metal mesh 1 and the second metal mesh 2 fixed in the ionization source chamber 3 are arranged in a spaced-apart parallel manner. The first metal mesh 1 and the second metal mesh 2 are both installed and fixed in the ionization source chamber 3 with insulating material, and maintain a sufficient safe distance from the surrounding metal. The first metal mesh 1 is loaded with a high voltage, and the second metal mesh 2 is loaded with a low voltage, so that a voltage difference is formed between the first metal mesh 1 and the second metal mesh 2. The spacing between the first metal mesh 1 and the second metal mesh 2 is determined by the air pressure in the ionization source chamber 3 when no sample and carrier gas are introduced, and the minimum spacing when no discharge is generated is the optimal spacing. The ionization source chamber 3 is provided with an injection port 31, a carrier gas inlet 32, and an ion outlet 33. The injection port 31 is located between the first metal mesh 1 and the second metal mesh 2, and the gaseous sample enters the space between the first metal mesh 1 and the second metal mesh 2 through the injection port 31. The carrier gas inlet 32 ​​is connected to an external carrier gas input device. External carrier gas enters the ionization source chamber 3 through the carrier gas inlet 32, assisting in directing the generated ions out of the ionization source chamber 3 through the ion outlet 33, allowing the generated ions to enter the next-stage system. The carrier gas inlet 32 ​​is located outside the second metal mesh 2, and the ion outlet 33 is located outside the first metal mesh 1. In some embodiments, the central axes of the carrier gas inlet 32 ​​and the ion outlet 33 coincide, and both central axes are perpendicular to the first metal mesh 1 and the second metal mesh 2.

[0028] The working principle of the gas-phase ion source ionization device provided in this embodiment is as follows: the first metal mesh 1 is loaded with a high voltage, and the second metal mesh 2 is loaded with a low voltage. The gaseous sample enters the ionization source chamber 3 from the injection port 31 and is located between the first metal mesh 1 and the second metal mesh 2. At this time, the working pressure in the ionization source chamber 3 changes due to the entry of the gaseous sample. The change in pressure causes the first metal mesh 1 to discharge the second metal mesh 2, that is, the change in pressure in the ionization source chamber 3 becomes the switching condition for the first metal mesh 1 and the second metal mesh 2 to discharge. The gaseous sample located between the first metal mesh 1 and the second metal mesh 2 is ionized to form ions due to the discharge of the first metal mesh 1 to the second metal mesh 2. The ionized ions fly rapidly to the ion outlet 33 under the assistance of the voltage of the first metal mesh 1 and the carrier gas inputted by the carrier gas inlet 32, and are drawn out of the ionization source chamber 3 through the ion outlet 33 and enter the next-level system. The gas-phase ion source ionization device provided in this embodiment adopts a high-voltage metal mesh as the ionization source. Compared with traditional gas-phase ionization sources, it has the advantages of easy miniaturization, simple design, low cost, no consumables, and no maintenance. It greatly reduces the cost and can significantly extend the maintenance cycle, which is of great significance to the application field of miniaturized mass spectrometers.

[0029] During the operation of the gas-phase ion source ionization device provided in this embodiment, the voltage difference between the first metal mesh 1 and the second metal mesh 2 remains constant during the ionization process, and the voltage difference can be precisely adjusted according to actual needs. The gap distance between the first metal mesh 1 and the second metal mesh 2 is mainly determined by the vacuum chamber working pressure of the ionization source chamber 3 and the voltage difference applied between the two metal meshes. In some embodiments, the voltage difference between the first metal mesh 1 and the second metal mesh 2 is 2 to 3 kV. At this time, considering the insulation gap between the first metal mesh 1 and the ionization source chamber 3 and the insulation gap between the second metal mesh 2 and the ionization source chamber 3, the gap distance between the first metal mesh 1 and the second metal mesh is 1.5 to 3 mm.

[0030] In some embodiments, the first metal mesh 1 and the second metal mesh 2 are made of the same material and have the same shape. For example, both the first metal mesh 1 and the second metal mesh 2 are formed of 316L stainless steel in a circular mesh structure. The first metal mesh 1 and the second metal mesh 2 may also be made of different materials, such as the first metal mesh 1 being made of stainless steel and the second metal mesh being made of another low-adhesion metal material. The first metal mesh 1 and the second metal mesh 2 may also have different shapes, such as the first metal mesh 1 being a circular disc and the second metal mesh 2 being a rectangular mesh disc.

[0031] Example 2

[0032] This embodiment 2 is a mass spectrometer formed on the basis of embodiment 1, such as Figure 1-3As shown, the gas phase ion source ionization device described in Example 1 is used to form the device, and also includes a sample introduction device 4, a carrier gas introduction device 5, an ion transmission device 6, a mass analyzer 7, an ion receiving device 8 and a vacuum pump 9.

[0033] like Figure 3 As shown, the sample introduction device 4 is a valve pipeline structure, the outlet of which is connected to the injection port 31. The gaseous sample is introduced into the ionization source chamber 3 through the injection port 31 and enters between the first metal mesh 1 and the second metal mesh 2 through the sample introduction device 4. The carrier gas introduction device 5 is a valve pipeline structure, the outlet of which is connected to the carrier gas inlet 32. The carrier gas is introduced into the ionization source chamber 3 through the carrier gas inlet 32 ​​through the carrier gas introduction device 5, and is used to assist in extracting the generated ions from the ionization source chamber 3 and entering the ion transmission device 6. The carrier gas introduced by the carrier gas introduction device 5 is mainly an inert gas, such as helium, argon, etc. However, when it is necessary to obtain the molecular ion peak of the substance to be measured and realize the soft ionization process, the carrier gas introduced by the carrier gas introduction device 5 is an inert gas mixed with methane, realizing a process similar to a chemical ionization source. The ion transmission device 6 is an ion lens, an ion guide device, or a combination of an ion lens and an ion guide device. The ions drawn out from the ion outlet 33 of the ion source chamber 3 enter the ion transmission device 6, and the ions are further collimated and shaped by the ion transmission device 6 and then transmitted to the mass analyzer 7. The mass analyzer 7 is used to analyze the incoming ions, and the mass analyzer 7 includes but is not limited to a quadrupole, an ion trap or a time-of-flight mass spectrometer. After the ions are analyzed in the mass analyzer 7, they are received by the ion receiving device 8. The ion receiving device 8 further forms a mass spectrum through a series of process operations such as signal amplification and reading. The ion receiving device 8 includes but is not limited to a Faraday cage, an electron multiplier or a microchannel plate plasma receiving structure. The vacuum pump 9 is used to achieve the vacuum environment required for the internal chamber of the mass spectrometer.

[0034] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0035] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A gas phase ion source ionization device, characterized in that: It comprises a first metal mesh (1), a second metal mesh (2) and an ionization source chamber (3); The first metal mesh (1) and the second metal mesh (2) are fixed in parallel and spaced apart in the ionization source chamber (3); the ionization source chamber (3) is provided with an injection port (31), a carrier gas inlet (32) and an ion outlet (33); the injection port (31) is located between the first metal mesh (1) and the second metal mesh (2); the carrier gas inlet (32) is located outside the second metal mesh (2); and the ion outlet (33) is located outside the first metal mesh (1); The first metal mesh (1) is loaded with a high level, and the second metal mesh (2) is loaded with a low level. A gaseous sample enters between the first metal mesh (1) and the second metal mesh (2) through the sample inlet (31). The change in the working gas pressure in the ionization source chamber (3) causes the first metal mesh (1) to discharge to the second metal mesh (2). The gaseous sample located between the first metal mesh (1) and the second metal mesh (2) is ionized. The ionized ions fly toward the ion outlet (33) under the assistance of the voltage of the first metal mesh (1) and the carrier gas entering through the carrier gas inlet (32), and are led out of the ionization source chamber (3) through the ion outlet (33) and enter the next-level system.

2. The gas phase ion source ionization device according to claim 1, characterized in that: The first metal mesh (1) and the second metal mesh (2) are made of the same or different materials.

3. The gas phase ion source ionization device according to claim 2, characterized in that: The first metal mesh (1) and the second metal mesh (2) are made of stainless steel.

4. The gas phase ion source ionization device according to claim 1, characterized in that: The first metal mesh (1) and the second metal mesh (2) have the same or different shapes.

5. The gas phase ion source ionization device according to any one of claims 1 to 4, characterized in that: The voltage difference applied between the first metal mesh (1) and the second metal mesh (2) is 2-3KV, and the gap between the first metal mesh (1) and the second metal mesh (2) is 1.5-3mm.

6. A mass spectrometer, characterized in that A gas phase ion source ionization device according to any one of claims 1 to 5, further comprising a sample introduction device (4), a carrier gas introduction device (5), an ion transmission device (6), a mass analyzer (7), an ion receiving device (8) and a vacuum pump (9); The sample introduction device (4) delivers the gas phase sample to be measured between the first metal mesh (1) and the second metal mesh (2) through the sample inlet (31); the carrier gas introduction device (5) inputs the carrier gas through the carrier gas inlet (32); the ionized ions fly to the ion outlet (33) under the auxiliary action of the voltage of the first metal mesh (1) and the carrier gas, and enter the ion transmission device (6) through the ion outlet (33); and are transmitted to the mass analyzer (7) for analysis through the collimation and shaping of the ion transmission device (6); after the analysis is completed, the ions enter the ion receiving device (8) from the mass analyzer (7); the ion receiving device (8) is used to form a mass spectrum; and the vacuum pump (9) is used to achieve the vacuum environment required for the internal chamber of the mass spectrometer.

7. The mass spectrometer according to claim 6, characterized in that The ion transmission device (6) is an ion lens, an ion guide device, or a combination of an ion lens and an ion guide device.

8. The mass spectrometer according to claim 6, characterized in that The mass analyzer (7) is a quadrupole, an ion trap or a time-of-flight mass spectrometer.

9. The mass spectrometer according to claim 6, characterized in that The ion receiving device (8) is a Faraday cage, an electron multiplier or a microchannel plate.

10. The mass spectrometer according to claim 6, wherein The carrier gas introduced by the carrier gas introduction device (5) is an inert gas or an inert gas mixed with methane.

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