Dielectric Barrier Discharge Inner Ionization Device

Abstract

The present invention provides an internal ionization device with dielectric barrier discharge in the technical field of mass spectrometry instruments, comprising a device body and a mass spectrometry chamber. The device body includes a capillary, a dielectric tube and an electrode. An inner wall is fixedly arranged inside the mass spectrometry chamber. The device body is connected to the mass spectrometry chamber, the capillary is connected to the dielectric tube, and the electrode is fixedly arranged on the dielectric tube. By adopting the structural design that the device body is connected to the mass spectrometry chamber, the capillary is connected to the dielectric tube, the electrode is fixedly arranged on the dielectric tube, and an inner wall is fixedly arranged inside the mass spectrometry chamber, the present invention utilizes the principle of dielectric barrier discharge to form an ionization region on the inner wall of the vacuum chamber of the mass spectrometer, effectively avoiding the degradation of the instrument performance caused by ion transmission; the ionization region is large, the ionization is more sufficient, and a relatively hard ion source will not be formed; the pressure difference between the pressure of the first-stage chamber of the mass spectrometry chamber and the atmospheric pressure can also be used for sample transmission without external gas loading.

Description

Technical Field

[0001] The present invention relates to the technical field of mass spectrometry instruments, and specifically, to a dielectric barrier discharge internal ionization device. Background Art

[0002] Dielectric barrier discharge is a kind of non-equilibrium gas discharge that uses an insulating medium inserted into the discharge space. It is divided into atmospheric pressure discharge and low-pressure discharge: For atmospheric pressure discharge, helium, argon, etc. are introduced between the electrodes as carrier gas and reaction gas. First, the reaction gas is ionized into ions, and then the sample is ionized through a molecule-ion reaction with the sample. The sample ions are guided to the mass spectrometer interface by the carrier gas; The low-pressure discharge method avoids the use of carrier gas and generally uses the pressure difference between atmospheric pressure and the mass spectrometry chamber to transport the sample and ions. The sample is ionized into ions in the ionization region formed between the two electrodes and then reaches the mass spectrometer after passing through the insulating medium. Therefore, there are a large number of ion losses in the ion transport in the insulating medium, which affects the sensitivity of the instrument.

[0003] After searching the prior art, it is found that the Chinese invention patent publication number is CN109243964A, which discloses a dielectric barrier discharge ion source, an analytical instrument and an ionization method, including a dielectric barrier discharge tube and an electrode pair composed of a first electrode and a second electrode. After the electrode pair is energized, the sample can be ionized. The dielectric barrier discharge tube is connected to the vacuum part, and the air pressure range in the dielectric barrier discharge tube is 0.01 - 100 Pa. Although this invention makes up for the defects of the existing ion source in the low air pressure range, it cannot solve the problem of ion loss in the dielectric barrier discharge tube.

[0004] After searching the prior art, it is found that the Chinese invention patent publication number is CN1862760A, which discloses a chemical ionization method and a mass spectrometry ion source based on dielectric barrier discharge, including an ionization chamber and a reaction chamber. The ionization chamber is a dielectric barrier discharge device, including two electrodes, with a discharge channel between the two electrodes and at least one layer of insulating barrier medium. After the reaction gas is ionized into ions in the ionization chamber, the device uses the ions to react with the sample molecules in the reaction chamber. This invention has the problem that the ion transport loss of the reaction gas affects the efficiency of the ion-molecule reaction between the sample molecules and the reaction gas.

[0005] In summary, the above related technologies all adopt a structure in which the ion source is separated from the mass spectrometry chamber, and the generated ions are introduced into the mass spectrometry chamber after being transported, and there are defects in ion transport. Therefore, a technical solution needs to be proposed to improve the above technical problems, and the present invention has carried out an optimized design to improve the existing problems. Therefore, the present invention is ingeniously designed and has strong practicability, can solve the above problems, and has better actual use effects. Summary of the Invention

[0006] Aiming at the defects in the prior art, the purpose of the present invention is to provide a dielectric barrier discharge internal ionization device.

[0007] A dielectric barrier discharge internal ionization device provided according to the present invention includes a device body and a mass spectrometry chamber. The device body includes a capillary, a dielectric tube, and an electrode. An inner wall is fixedly arranged inside the mass spectrometry chamber.

[0008] The device body is connected to the mass spectrometry chamber. The capillary is connected to the dielectric tube, and the electrode is fixedly arranged on the dielectric tube.

[0009] In some embodiments, the capillary is connected to the upstream position of the dielectric tube, and the capillary and the dielectric tube are hermetically arranged.

[0010] In some embodiments, the capillary includes a stainless steel capillary, a quartz capillary, a polymer capillary, other metal capillaries, and alloy capillaries, and the capillary includes a disc-shaped capillary, a straight capillary, and a bent capillary.

[0011] In some embodiments, the dielectric tube includes a quartz dielectric tube, a glass dielectric tube, a ceramic dielectric tube, and a polymer dielectric tube.

[0012] In some embodiments, the electrode is fixedly arranged on the outer wall of the dielectric tube, and the electrode is isolated from the inner wall.

[0013] In some embodiments, the electrode includes a helically wound electrode, a cylindrical electrode, and a spring-shaped electrode, and the electrode includes a copper electrode, a silver electrode, a stainless steel electrode, and an alloy electrode.

[0014] In some embodiments, the capillary and the dielectric tube are partially overlapped or completely non-overlapped.

[0015] In some embodiments, the outer diameter of the capillary is less than or equal to the inner diameter of the dielectric tube.

[0016] In some embodiments, the mass spectrometry chamber includes a first-stage vacuum cavity, a second-stage vacuum cavity, and an ionization source. One end of the dielectric tube is connected to the downstream position of the capillary, and the other end of the dielectric tube is connected to the first-stage vacuum cavity.

[0017] In some embodiments, one end of the dielectric tube is connected inside the mass spectrometry chamber, and the dielectric tube and the inner wall are not limited to being indented, protruding, or flush.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention is designed such that the device body is connected to the mass spectrometry chamber, the capillary is connected to the dielectric tube, the electrode is fixedly arranged on the dielectric tube, and the inner wall is fixedly arranged inside the mass spectrometry chamber. By using the principle of dielectric barrier discharge, an ionization region is formed on the inner wall of the vacuum chamber of the mass spectrometer, effectively avoiding the degradation of instrument performance caused by ion transmission. The ionization region is relatively large, enabling more sufficient ionization, and at the same time, a relatively hard ion source will not be formed. Moreover, the pressure difference between the pressure in the first-stage chamber of the mass spectrometry chamber and the atmospheric pressure can be utilized for sample transmission without the need for external carrier gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects, and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0021] Figure 1 Schematic diagram of a mass spectrometer for the specific application of the dielectric barrier discharge internal ionization device of the present invention;

[0022] Figure 2 Schematic diagram of the relative position relationship between the capillary and the dielectric tube in the dielectric barrier discharge internal ionization device of the present invention;

[0023] Figure 3 Schematic diagram of the relative position relationship between the dielectric tube and the inner wall in the dielectric barrier discharge internal ionization device of the present invention.

[0024] Reference Signs:

[0025] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0027] As Figure 1 shown is a schematic diagram of a mass spectrometer for the specific application of the dielectric barrier discharge internal ionization device of the present invention. As Figure 2 shown is a schematic diagram of the relative position relationship between the capillary and the dielectric tube in the dielectric barrier discharge internal ionization device of the present invention. As Figure 3 shown is a schematic diagram of the relative position relationship between the dielectric tube and the inner wall in the dielectric barrier discharge internal ionization device of the present invention. It includes a device body and a mass spectrometry chamber 6. The device body includes a capillary 1, a dielectric tube 2, and an electrode 4. An inner wall 3 is fixedly arranged inside the mass spectrometry chamber 6. The device body is connected to the mass spectrometry chamber 6, the capillary 1 is connected to the dielectric tube 2, and the electrode 4 is fixedly arranged on the dielectric tube 2.

[0028] The capillary 1 is connected and arranged at the upstream position of the medium tube 2, and the capillary 1 and the medium tube 2 are hermetically arranged. The specific dimensions of the capillary 1 are: 0.25 mm i.d.×100 mm, and the specific dimensions of the medium tube 2 are 3 mm i.d.×50 mm. The capillary 1 includes a stainless-steel capillary, a quartz capillary, a polymer capillary, other metal capillaries, and alloy capillaries, and the capillary 1 includes a disc-shaped capillary, a straight capillary, and a bent capillary. The medium tube 2 includes a quartz medium tube, a glass medium tube, a ceramic medium tube, and a polymer medium tube.

[0029] The electrode 4 is fixedly arranged on the outer wall of the medium tube 2, and the electrode 4 is isolated from the inner wall 3. A radio-frequency voltage is applied to drive the electrode 4, the voltage frequency is 1.0 - 1.2 MHz, and the amplitude is 2 kV. The radio-frequency voltage is not limited to other suitable waveforms such as sine waves, square waves, and triangular waves. The electrode 4 includes a helically wound electrode, a cylindrical electrode, and a spring-shaped electrode, and the electrode 4 includes a copper electrode, a silver electrode, a stainless-steel electrode, and an alloy electrode.

[0030] The capillary 1 and the medium tube 2 are partially overlapped or completely non-overlapped. The positional relationship between the capillary 1 and the medium tube 2 can be tangent or intersecting in cross-section, and the length of the cross-section intersection is not limited. The outer diameter of the capillary 1 is less than or equal to the inner diameter of the medium tube 2. The inner diameter of the capillary 1 of the device body is related to the air pressure requirement of the mass spectrometry chamber 6 and is not limited to a fixed size and length.

[0031] The mass spectrometry chamber 6 includes a first-stage vacuum cavity, a second-stage vacuum cavity, and an ionization source. One end of the medium tube 2 is connected and arranged at the downstream position of the capillary 1, and the other end of the medium tube 2 is connected to the first-stage vacuum cavity. The mass spectrometry chamber 6 is provided with a molecular pump with a pumping speed of 67 L / s at the bottom of the second-stage vacuum cavity. One end of the fore pump of the molecular pump is connected to the molecular pump, and the pumping speed of the fore pump is 50 L / min. The air pressure in the first-stage cavity is 2000 - 7000 Pa. One end of the medium tube 2 is connected and arranged inside the mass spectrometry chamber 6, and the medium tube 2 and the inner wall 3 are not limited to being indented, protruding, or flush. The positional relationship between the medium tube 2 and the inner wall 3 of the mass spectrometry chamber can be that one end of the medium tube 2 is indented, flush, or protruding from the inner wall 3 of the mass spectrometry chamber.

[0032] Principle of operation

[0033] The sample to be measured is introduced through the capillary 1 and ionized in the ionization region. The dielectric barrier discharge ion source is composed of the electrode 4, the dielectric tube 2 and the inner wall 3 of the mass spectrometry chamber, and an ionization region is formed between the electrode 4 and the inner wall 3 of the mass spectrometry chamber. The "flow" phenomenon occurs in this ionization region with the plasma aggregation and air purging effects. The ionization region transfers towards the inside of the mass spectrometry chamber and finally stabilizes at the inner wall 3 of the mass spectrometry chamber. The sample to be measured finally reaches the ionization region 5 through the capillary 1 and is ionized into ions. After the ions are formed, they directly enter the ion transmission device of the mass spectrometer, eliminating the ion loss caused by the transmission through the dielectric tube after the ions are formed.

[0034] It should be noted that the capillary 1 in the device of the present invention is in a non-grounded state. Therefore, the dielectric barrier discharge ionization occurs between the electrode 4 and the inner wall 3 of the mass spectrometry chamber.

[0035] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application.

[0036] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments. Those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined arbitrarily with each other.

Claims

1. A dielectric barrier discharge internal ionization device, characterized in that, it includes a device body and a mass spectrometry chamber (6), the device body includes a capillary (1), a dielectric tube (2) and an electrode (4), and an inner wall (3) is fixedly arranged inside the mass spectrometry chamber (6); The device body is connected to the mass spectrometry chamber (6), the capillary (1) is connected to the dielectric tube (2), and the electrode (4) is fixedly arranged on the dielectric tube (2); The capillary (1) is connected to the upstream position of the dielectric tube (2), and the capillary (1) and the dielectric tube (2) are hermetically arranged; The electrode (4), the dielectric tube (2) and the inner wall (3) form a dielectric barrier discharge ion source, and an ionization region is formed between the electrode (4) and the inner wall (3). The ionization region undergoes a flow phenomenon with the aggregation and purging of plasma, and the ionization region transfers into the mass spectrometry chamber (6) and finally stabilizes at the inner wall (3); The capillary (1) includes a metal capillary, a quartz capillary, and a polymer capillary, and the capillary (1) includes a straight capillary and a bent capillary; The dielectric tube (2) includes a quartz dielectric tube, a glass dielectric tube, a ceramic dielectric tube, and a polymer dielectric tube; The outer diameter of the capillary (1) is less than or equal to the inner diameter of the dielectric tube (2); The specific dimensions of the capillary (1) are 0.25mm i.d.×100mm, and the specific dimensions of the dielectric tube (2) are 3mm i.d.×50mm; The mass spectrometry chamber (6) includes a first-stage vacuum cavity, a second-stage vacuum cavity, and an ionization source. One end of the dielectric tube (2) is connected to the downstream position of the capillary (1), and the other end of the dielectric tube (2) is connected to the first-stage vacuum cavity.

2. The dielectric barrier discharge internal ionization device according to claim 1, characterized in that, the electrode (4) is fixedly arranged on the outer wall of the dielectric tube (2), and the electrode (4) is isolated from the inner wall (3).

3. The dielectric barrier discharge internal ionization device according to claim 1, characterized in that, the capillary (1) and the dielectric tube (2) are partially overlapped or not overlapped at all.

4. The dielectric barrier discharge internal ionization device according to claim 1, characterized in that, one end of the dielectric tube (2) connected to the inside of the mass spectrometry chamber (6), and the dielectric tube (2) and the inner wall (3) are not limited to being indented, protruding or flush.

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