A kind of ion source device based on direct current hollow electrode discharge

Abstract

The application discloses a kind of ion source device based on direct current hollow electrode discharge, including cavity, the bottom wall of cavity is equipped with front end support piece, front end support piece is equipped with anode plate, cathode plate, ion outlet electrode and lens group in sequence, still include matched direct current power supply;Anode plate and cathode plate are all hollow electrode formed by hollow electrode piece;Lens group includes circular ring electrode piece, insulating gasket, lens outlet;The outer center of anode plate is opened with gas sampling hole;The side wall of cavity is equipped with feed-in piece interface.The ion source device is under the environment of low vacuum (10 ‑2 Pa) using high-voltage electric field formed by glow discharge to produce electron bombardment sample molecules to produce gas cation, avoids sample pretreatment cumbersome and additional carrier gas sampling, so that the whole detection process is fast, efficient and real-time.

Description

Technical Field

[0001] This invention relates to a mass spectrometry system and analytical detection technology, and more particularly to an ion source device based on DC hollow electrode discharge. Background Technology

[0002] Compared to traditional detection techniques, mass spectrometry offers higher sensitivity, stronger selectivity, and shorter detection times. Gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and inductively coupled plasma mass spectrometry (ICP-MS) are widely used in environmental monitoring, food safety, and biomedicine. However, GC-MS, LC-MS, and ICP-MS require sample pretreatment procedures such as digestion, extraction, concentration, and separation, and consume large amounts of carrier gas during detection, taking several hours to complete. For the detection of small gas molecules, GC-MS remains the primary method in the mass spectrometry field. However, besides its complex pretreatment, long detection time, and difficulty in analyzing fragment ions using multiple spectra, GC-MS is particularly unsatisfactory for small molecules, primarily targeting large organic molecules such as VOCs.

[0003] Traditional DC glow discharge ion sources can only be used to detect metallic elements and require argon as a carrier gas, making them unable to detect small gas molecules.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide an ion source device based on DC hollow electrode discharge to solve the problem of gas small molecule detection in the prior art, as well as the problems of complex gas sample pretreatment process and long detection time in existing gas small molecule detection methods.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The ion source device based on DC hollow electrode discharge of the present invention includes a cavity, the bottom wall of which is provided with a front end support member, and the front end support member is provided with an anode plate, a cathode plate, an ion outlet electrode and a lens group in sequence, and also includes a matching DC power supply.

[0008] Both the anode plate and the cathode plate are hollow electrodes composed of hollow electrode sheets;

[0009] The lens assembly includes a circular electrode plate, an insulating pad, and a lens outlet;

[0010] A gas inlet hole is provided at the outer center of the anode plate;

[0011] The cavity is provided with a feed interface on its side wall.

[0012] Compared with existing technologies, the ion source device based on DC hollow electrode discharge provided by this invention has a hollow ionization chamber structure and a gas inlet. This ion source device operates under low vacuum (10... -2 In an environment of Pa, electrons generated by glow discharge formed by a high-voltage electric field bombard sample molecules to produce gaseous cations, avoiding cumbersome sample pretreatment and additional carrier gas injection, making the entire detection process fast, efficient and real-time. Attached Figure Description

[0013] Figure 1 A block diagram of the overall structure of an ion source device based on DC hollow electrode discharge provided in an embodiment of the present invention;

[0014] Figure 2 This is a schematic diagram of the DC hollow electrode discharge ion source device according to an embodiment of the present invention;

[0015] Figure 3 This is a mass spectrum of grain combustion products excited by the DC hollow electrode discharge ion source described in this invention example.

[0016] In the picture:

[0017] 1. Chamber body; 2. Ionization chamber front end support; 3. Anode plate; 4. Cathode plate; 5. Ion outlet electrode; 6. Gas inlet; 7. Circular electrode sheet; 8. Insulating gasket; 9. Lens outlet; 10. Feed interface. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them, and do not constitute a limitation on the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0019] First, the following explanations are provided for the terms that may be used in this article:

[0020] The term "and / or" means that either or both can be achieved simultaneously. For example, X and / or Y means that it includes both "X" or "Y" as well as the three cases of "X and Y".

[0021] The terms “including,” “comprising,” “containing,” “having,” or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, “including a technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction conditions, processing conditions, parameter, algorithm, signal, data, product or article of manufacture, etc.)” should be interpreted as including not only the expressly listed technical feature element, but also other technical feature elements that are not expressly listed and are well-known in the art.

[0022] The term "composed of" excludes any technical features not expressly listed. When used in a claim, it closes the claim to exclude all technical features other than those expressly listed, except for associated conventional impurities. If the term appears only in a clause of a claim, it limits the claim to the elements expressly listed in that clause; elements recited in other clauses are not excluded from the overall claim.

[0023] The contents not described in detail in the embodiments of this invention are prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of this invention, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments used in the embodiments of this invention are not specified, they are all conventional products that can be purchased commercially.

[0024] The ion source device based on DC hollow electrode discharge of the present invention includes a cavity, the bottom wall of which is provided with a front end support member, and the front end support member is provided with an anode plate, a cathode plate, an ion outlet electrode and a lens group in sequence, and also includes a matching DC power supply.

[0025] Both the anode plate and the cathode plate are hollow electrodes composed of hollow electrode sheets;

[0026] The lens assembly includes a circular electrode plate, an insulating pad, and a lens outlet;

[0027] A gas inlet hole is provided at the outer center of the anode plate;

[0028] The cavity is provided with a feed interface on its side wall.

[0029] The hollow electrode has an outer diameter of 40 mm and an inner diameter of 10 mm. The entire space of the ionization chamber formed by the hollow electrode is 30-60 mm. 3 ;

[0030] The ionization chamber ensures that the sample gas can be fully excited. When the gas sample is ionized to produce cations, it will be subjected to a positive electric field force applied to the anode plate, and the generated cations will be pushed to the ion outlet electrode through the gas inlet hole.

[0031] The DC power supply operates in the range of 500 to 2500V, and an appropriate excitation voltage is selected according to the different objects being detected.

[0032] The ion source device operates at 10 -2 In a low vacuum environment of Pa, the gas injection rate is controlled at 1 ml / min by a mass flow controller to meet the vacuum conditions for gas ionization and ensure that enough gas sample enters the hollow ionization chamber.

[0033] The lens group includes eight circular electrode plates, which are insulated with polytetrafluoroethylene (PTFE) in the middle. Adjacent electrode plates are connected by precision resistors with a resistance of 1kΩ-10MΩ. A DC current of 400-2500V is applied to both ends of the lens group, which creates an accelerating electric field with focusing function inside the lens group. This allows ions to be better concentrated and quickly pass through and enter the quadrupole mass analyzer.

[0034] The following steps are included when performing gas mass spectrometry detection:

[0035] Step 1: Use a mechanical pump to evacuate the gas pressure in the ionization chamber to 10-30 Pa, then turn on the molecular pump to continue evacuating until the gas pressure in the ionization chamber drops to 10 Pa. -2 Pa;

[0036] Step 2: Power is supplied to the anode and cathode plates of the DC hollow electrode ion source through the feeder, generating a potential difference of over 700V;

[0037] Step 3: The gaseous products generated after grain combustion are introduced into the DC hollow electrode ionization chamber using MFC and capillary tube, with the MFC flow rate being 1 ml / min.

[0038] Step 4: To verify whether small gas molecules can be ionized by a DC hollow electrode ion source, the DC hollow electrode ion source is used to detect nitrogen oxide gas generated from the grain. Specifically, this includes:

[0039] The gas produced by burning grain is passed into an ion source. The cations generated after the gas is ionized will enter the mass analyzer for further detection.

[0040] Considering the interference caused by other interfering ions to the detection, a selected ion scanning mode is adopted, and N is selected. + (14), NO + (30), O2 + (32), NO2 + (46) Conduct testing;

[0041] The DC hollow electrode discharge ion source can fully detect small gas molecules and can be used to detect nitrogen content in grains.

[0042] In summary, the ion source device based on DC hollow electrode discharge according to the embodiments of the present invention comprises a cathode plate, an anode plate, an ion outlet electrode, and a lens assembly. The ionization chamber is designed as a hollow structure and is equipped with a gas inlet. This ion source device operates under low vacuum (10... -2 In an environment of high voltage electric field, electrons generated by glow discharge bombard sample molecules to produce gaseous cations, avoiding cumbersome sample pretreatment and additional carrier gas injection, making the entire detection process fast, efficient and real-time.

[0043] The Direct Current Hollow Electrode Discharge Ion Source (DCHED) provides a highly efficient discharge region for the ionization of gas samples by constructing a hollow electrode discharge chamber. Electrons generated by the DC voltage acting on the anode and cathode electrodes collide with the gas, producing ions. These ions are then rapidly introduced into the quadrupole mass analyzer through an accelerating electric field created by a lens assembly. Due to its high energy, high throughput, high resolution, and ability to ionize a variety of gas molecules, especially small gas molecules, the DCHED eliminates the need for sample pretreatment. Direct sample injection and controllable ionization energy (through DC voltage adjustment) result in fewer ion fragments and interfering ions, simplifying spectral processing. Therefore, the DCHED is perfectly capable of detecting small gas molecules.

[0044] To more clearly demonstrate the technical solution and its effects provided by the present invention, the embodiments of the present invention will be described in detail below with reference to specific examples.

[0045] In this invention, both the anode plate and the cathode plate are hollow, forming a gas discharge region, i.e., an ionization chamber. The ionization chamber is composed of the anode plate and the cathode plate, with an inner diameter of 10 mm and a total space of approximately 30-60 mm. 3 This design is primarily for gas samples. First, gases diffuse easily, so the ionization chamber space shouldn't be too large; otherwise, gas diffusion will occur, affecting the vacuum level. Second, the excitation of gas molecules depends not only on voltage and vacuum but also on gas number density. If the ionization chamber is too small, the low gas number density will prevent excitation even with sufficient voltage. Therefore, a size of 30-60 mm is chosen. 3The ionization chamber is equipped with a gas inlet located on the anode plate. When the gas is ionized, the resulting cations are acted upon by the positive electric field applied to the anode plate and move to the ion outlet electrode. The gas inlet has a G1 / 8 thread and is fitted with a G1 / 16-inch tubing for injection. The gas injection rate is controlled at 1 ml / min using an MFC (Micro-Fuel Cell). The ionized cations, under the influence of the electric field, pass through the ion outlet electrode and enter the lens assembly. To facilitate ion aggregation, the ion outlet electrode is designed with a tapered opening with an inner diameter of 1.5 mm. The tapered opening of the ion outlet electrode also serves another important purpose: because the DC hollow electrode ion source is located at 10⁻⁶ ppm... 2 The excitation gas operates in an environment of 10⁻³ Pa, while the ion transmission lens group operates in an environment of 10⁻³ Pa. The conical opening of the ion outlet electrode can form a two-stage vacuum.

[0046] The ion transmission lens assembly consists of a set of lens plates (eight circular plates) insulated with PTFE gaskets. Adjacent electrode plates are connected by resistors with a resistance of 1kΩ-10MΩ. A DC voltage of 400-2500V is applied across the lens assembly, and the ion throughput can be increased by adjusting the voltage. The function of the lens assembly is to ensure that ions exiting the ion source continuously accumulate and pass through rapidly, thereby reducing the edge field effect caused by ions entering the quadrupole mass analyzer and improving the sensitivity of the instrument.

[0047] An adjustable DC voltage of 500-2500V is applied between the anode and cathode plates of the DC hollow electrode ion source. This allows for the selection of the optimal excitation voltage based on different gases, reducing the generation of fragment ions. Simultaneously, the ionized cations are propelled towards the ion outlet electrode by the electric field. Similarly, applying a DC voltage of 100-500V to the ion outlet electrode accelerates ion passage.

[0048] The vacuum system module is characterized in that: the vacuum system of the entire machine is provided and maintained by one mechanical pump and two 80 molecular pumps. The entire ion source and ion transport device adopts a two-stage vacuum design, with the vacuum in the hollow discharge region being 10⁻⁶. 2 Pa, the vacuum of the ion transport lens group is 10. -3 Pa. To ensure a two-stage vacuum, a conical inlet is used for separation. The inlet has an inner diameter of 1.5 mm. This ensures both the excitation requirements of the ion source and the normal operation of the ion transmission lens assembly. The entire vacuum system uses Pirani and Penning gauges for vacuum pressure measurement, and the vacuum gauge displays the system's vacuum level in real time.

[0049] In some embodiments of the ion source device based on DC hollow electrode discharge, a feeder is used to power the ion source and the ion transport system.

[0050] The ion source based on DC hollow electrode discharge can excite NO and NO2 gases, and can be used to detect nitrogen content in food. It utilizes a small tubular furnace to burn grain samples, and the resulting gaseous products are directly passed into the DC hollow electrode ion source for direct ionization to generate NO. + and NO2 + Ions. Enables rapid and efficient detection of small gaseous molecules. It not only avoids the cumbersome sample pretreatment process but also provides a fast, real-time, online detection method.

[0051] Example 1

[0052] like Figures 1 to 3 As shown:

[0053] A mass spectrometry system based on a DC hollow electrode discharge ion source is provided, including modules such as a sample introduction device, a DC hollow electrode discharge ion source, an ion transmission lens group, a quadrupole mass analyzer, an ion detector, a vacuum system, and an instrument power control system.

[0054] In one embodiment, such as Figure 2 As shown, a DC hollow electrode discharge ion source device is provided, including a cavity 1, an ionization chamber front end support 2, an anode plate 3, a cathode plate 4, an ion outlet electrode 5, a gas inlet 6, a circular electrode sheet 7, an insulating pad 8, a lens outlet 9, and a feed interface 10.

[0055] In one embodiment, such as Figure 1 As shown, when performing gas mass spectrometry detection based on the aforementioned ion source device using DC glow discharge, the following steps are included:

[0056] Step 1: Use a mechanical pump to evacuate the gas pressure in the ionization chamber to approximately 10–30 Pa, then turn on the molecular pump to continue evacuating until the gas pressure in the ionization chamber drops to 10 Pa. -2 Approximately Pa.

[0057] Step 2: Power is supplied to the anode and cathode plates of the DC hollow electrode ion source through the feeder, generating a potential difference of over 700V.

[0058] Step 3: The gaseous products generated after grain combustion are introduced into the DC hollow electrode ionization chamber using an MFC and capillary tube. The flow rate of the MFC is 1 ml / min.

[0059] Step 4: To verify whether small gas molecules can be ionized by a DC hollow electrode ion source, this case specifically uses a DC hollow electrode ion source to detect nitrogen oxides generated from grain combustion. The gas produced after grain combustion is passed into the ion source. The cations generated after ionization will then enter the mass analyzer for further detection. Considering the interference from other interfering ions, a selected ion scan mode is used, selecting N... + (14), NO + (30), O2 + (32), NO2 + (46), such as Figure 3 As shown, the DC hollow electrode discharge ion source can fully detect small gas molecules and can be used to detect the nitrogen content in grains.

[0060] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. An ion source device based on DC hollow electrode discharge, characterized in that, The device includes a cavity, the bottom wall of which is provided with a front-end support member, and the front-end support member is provided with an anode plate, a cathode plate, an ion outlet electrode and a lens group in sequence, and also includes a matching DC power supply. Both the anode plate and the cathode plate are hollow electrodes composed of hollow electrode sheets; The lens assembly includes a circular electrode plate, an insulating pad, and a lens outlet; A gas inlet hole is provided at the outer center of the anode plate; The cavity is provided with a feed interface on its side wall.

2. The ion source device based on DC hollow electrode discharge according to claim 1, characterized in that, The hollow electrode has an outer diameter of 40 mm and an inner diameter of 10 mm. The entire space of the ionization chamber formed by the hollow electrode is 30-60 mm. 3 ; The ionization chamber ensures that the sample gas can be fully excited. When the gas sample is ionized to produce cations, it will be subjected to a positive electric field force applied to the anode plate, and the generated cations will be pushed to the ion outlet electrode through the gas inlet hole.

3. The ion source device based on DC hollow electrode discharge according to claim 2, characterized in that, The DC power supply operates in the range of 500 to 2500V, and an appropriate excitation voltage is selected according to the different objects being detected.

4. The ion source device based on DC hollow electrode discharge according to claim 3, characterized in that, The ion source device operates at 10 -2 In a low vacuum environment of Pa, the gas injection rate is controlled at 1 ml / min by a mass flow controller to meet the vacuum conditions for gas ionization and ensure that enough gas sample enters the hollow ionization chamber.

5. The ion source device based on DC hollow electrode discharge according to claim 4, characterized in that, The lens group includes eight circular electrode plates, which are insulated with polytetrafluoroethylene (PTFE) in the middle. Adjacent electrode plates are connected by precision resistors with a resistance of 1kΩ-10MΩ. A DC current of 400-2500V is applied to both ends of the lens group, which creates an accelerating electric field with focusing function inside the lens group. This allows ions to be better concentrated and quickly pass through and enter the quadrupole mass analyzer.

6. The ion source device based on DC hollow electrode discharge according to any one of claims 1 to 5, characterized in that, The following steps are included when performing gas mass spectrometry detection: Step 1: Use a mechanical pump to evacuate the gas pressure in the ionization chamber to 10-30 Pa, then turn on the molecular pump to continue evacuating until the gas pressure in the ionization chamber drops to 10 Pa. -2 Pa; Step 2: Power is supplied to the anode and cathode plates of the DC hollow electrode ion source through the feeder, generating a potential difference of over 700V; Step 3: The gaseous products generated after grain combustion are introduced into the DC hollow electrode ionization chamber using MFC and capillary tube, with the MFC flow rate being 1 ml / min. Step 4: To verify whether small gas molecules can be ionized by a DC hollow electrode ion source, the DC hollow electrode ion source is used to detect the nitrogen oxide gas produced from the grain. Specifically, this includes: The gas produced by burning grain is passed into an ion source. The cations generated after the gas is ionized will enter the mass analyzer for further detection. Considering the interference caused by other interfering ions to the detection, a selected ion scanning mode is adopted, and N is selected. + (14), NO + (30), O2 + (32), NO2 + (46) Conduct testing; The DC hollow electrode discharge ion source can fully detect small gas molecules and can be used to detect nitrogen content in grains.

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