High-sensitivity EIQ-MS mass spectrum structure in low-vacuum environment

Abstract

The invention provides a high-sensitivity EIQ-MS mass spectrum structure in a low vacuum environment, and belongs to the technical field of mass spectrometers. Comprising a sample introduction capillary tube, a first vacuum chamber, a second vacuum chamber, a lamp filament, a reflecting electrode, a quadrupole rod mass analyzer, a glass shell and an MCP detector, the sample introduction capillary tube is arranged on the input side of the first vacuum chamber, and an ionization area is formed in the position, located on the rear side of the sample introduction capillary tube, of the first vacuum chamber; the quadrupole rod mass analyzer and the MCP detector are sequentially arranged in a first vacuum chamber on the rear side of an ionization area, the quadrupole rod mass analyzer is wrapped by the glass shell, the first vacuum chamber is sleeved with and fixedly connected with the second vacuum chamber, and the lamp filament is arranged in the second vacuum chamber and corresponds to the position above the ionization area. The reflecting electrode is arranged below the ionization area in the second vacuum chamber, and small holes for electron beams to pass through are formed in the upper and lower side walls, corresponding to the ionization area, of the first vacuum chamber. According to the invention, high-efficiency and high-sensitivity analysis can be realized under a low-vacuum condition, and the service life of the ion source is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of mass spectrometry technology, specifically relating to a high-sensitivity EIQ-MS mass spectrometry structure under low vacuum conditions. Background Technology

[0002] Mass spectrometers, as a representative of modern analytical instruments, have wide applications in fields such as medicine, chemistry, and environmental bioanalysis.

[0003] In conventional EIQ-MS mass spectrometers, due to the advantages of simple structure and small size, the ionization module is designed in a simplified manner, which sacrifices the vacuum degree in the ionization chamber. Therefore, it is impossible to guarantee the high vacuum degree requirements of the mass analyzer and detector, resulting in poor instrument sensitivity. At the same time, the filament of the EI source is also affected by sample erosion and low vacuum. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-sensitivity EIQ-MS mass spectrometry structure for low-vacuum environments, which solves the problem that quadrupole mass analyzers and detectors can only be used normally in high-vacuum environments, while allowing the filament to be placed independently in a high-vacuum environment.

[0005] The objective of this invention can be achieved through the following technical solution: A high-sensitivity EIQ-MS mass spectrometry structure for low vacuum environments, comprising an injection capillary, a first vacuum chamber, a second vacuum chamber, a filament, a reflective electrode, a quadrupole mass analyzer, a glass shell, and an MCP detector. The injection capillary is disposed on the input side of the first vacuum chamber, which forms an ionization region at the rear of the injection capillary. The quadrupole mass analyzer and the MCP detector are sequentially disposed in the first vacuum chamber at the rear of the ionization region. The glass shell encloses the quadrupole mass analyzer. The second vacuum chamber is fitted and fixed outside the first vacuum chamber. The filament is disposed in the second vacuum chamber above the ionization region, and the reflective electrode is disposed in the second vacuum chamber below the ionization region. Small holes for electron beams to pass through are formed on the upper and lower sidewalls of the first vacuum chamber corresponding to the ionization region.

[0006] Preferably, a first focusing electrode is provided between the filament and the small hole in the side wall of the first vacuum chamber, and between the reflecting electrode and the small hole in the side wall of the first vacuum chamber.

[0007] Preferably, a second focusing electrode is further provided between the ionization region and the quadrupole mass analyzer.

[0008] Preferably, the first vacuum chamber and the second vacuum chamber are maintained at a constant vacuum level by continuous evacuation by vacuum pumps, and the pressure value of the first vacuum chamber is one order of magnitude lower than the pressure value of the second vacuum chamber.

[0009] Preferably, the voltage applied to the reflective electrode is greater than the voltage applied to the filament.

[0010] Preferably, the glass shell is vacuum glass.

[0011] Compared with the prior art, the present invention has the following beneficial effects: by setting up two vacuum chambers of different magnitudes, the influence of the low vacuum environment of the first vacuum chamber on the instrument analyzer is eliminated, and the quadrupole mass analyzer and MCP detector can work normally even in poor vacuum environments; the quadrupole mass analyzer is encased in vacuum glass, which can effectively reduce the collision between ions and low vacuum gas molecules, avoid low vacuum discharge phenomena, ion scattering, energy loss or fragmentation, and ensure that ions are stably transported along the quadrupole axis and reach the detector; placing the filament in an independent high vacuum environment extends the filament's service life, prevents oxidation, and improves the filament's working stability; the first focusing electrode can further improve the electron bombardment efficiency, thereby improving the instrument's sensitivity.

[0012] Figure 1 This is a schematic diagram of the high-sensitivity EIQ-MS mass spectrometer structure under low vacuum conditions, as shown in the embodiment.

[0013] Figure 2 This is a cross-sectional view of the quadrupole mass analyzer section in an embodiment.

[0014] In the figure: 1. Sample inlet capillary; 2. First vacuum chamber; 2a. Ionization region; 3. Second vacuum chamber; 4. Filament; 5. Reflecting electrode; 6. Quadrupole mass analyzer; 7. Glass housing; 8. Detector; 9. Vacuum pump; 10. First focusing electrode; 11. Second focusing electrode. Detailed Implementation

[0015] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled 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.

[0016] Furthermore, it should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the terms "front end" and "back end" as used herein refer to the sequential order of the actual ion migration path, and are hereby clarified.

[0017] like Figure 1 , Figure 2 As shown, the high-sensitivity EIQ-MS mass spectrometry structure for low vacuum environments provided in this embodiment includes an injection capillary 1, a first vacuum chamber 2, a second vacuum chamber 3, a filament 4, a reflective electrode 5, a quadrupole mass analyzer 6, a glass shell 7, and a detector 8. The injection capillary 1 is located on the input side of the first vacuum chamber 2, which forms an ionization region 2a at the rear side of the injection capillary 1. The quadrupole mass analyzer 6 and the detector 8 are sequentially arranged inside the first vacuum chamber 2 at the rear side of the ionization region 2a. The glass shell 7 is wrapped around the quadrupole mass analyzer 6. The second vacuum chamber 3 is fitted and fixed to the outside of the first vacuum chamber 2. The filament 4 is located above the ionization region 2a in the second vacuum chamber 3, and the reflective electrode 5 is located below the ionization region 2a in the second vacuum chamber 3. Small holes for the electron beam to pass through are opened on the upper and lower side walls of the first vacuum chamber 2 corresponding to the ionization region 2a. It should be noted that in this embodiment, the first vacuum chamber 2 and the second vacuum chamber 3 are each connected to a vacuum pump 9, and the vacuum pump 9 continuously pumps air to maintain a constant vacuum level, and the pressure value of the first vacuum chamber 2 is one order of magnitude lower than the pressure value of the second vacuum chamber.

[0018] Furthermore, a first focusing electrode 10 is disposed between the filament 4 and the small hole on the side wall of the first vacuum chamber 2, and between the reflective electrode 5 and the small hole on the side wall of the first vacuum chamber 2. The voltage applied to the reflective electrode 5 is slightly greater than the voltage applied to the filament 4. A DC gradient of approximately 10V / cm is applied to the first focusing electrode 10. The first focusing electrode 10 is at a high voltage end near the filament and the reflective electrode, and at a low voltage end near the small hole. A DC gradient of 10V / cm is applied from the high voltage end to the low voltage end. See [reference needed] Figure 1In the dashed section, the electron beam is emitted from the filament 4, accelerated and focused into a narrow beam by the electrostatic lens of the first focusing electrode 10 above. It then passes through a small hole and bombards the sample molecules in the ionization region 2a to ionize the sample. Electrons that are not completely consumed pass out of the ionization region 2a, pass through the small hole below, are decelerated and focused by the first focusing electrode 10 below, and are then reflected back to the ionization region 2a by the reflecting electrode 5 to continue participating in ionization, forming a narrow electron cloud, thereby improving the ionization efficiency and the transmission efficiency of the ion beam.

[0019] A second focusing electrode 11 is also provided between the ionization region 2a and the quadrupole mass analyzer 6. The second focusing electrode 11 enables efficient transfer of the ionized sample to the quadrupole mass analyzer 6.

[0020] In this invention, the glass shell 7 encasing the quadrupole mass analyzer 6 is vacuum glass. This shell encapsulates the quadrupole mass analyzer 6 in a structure capable of operating normally in low-vacuum environments. Simultaneously, the detector 8 employs a single-unit MCP detector, requiring no high voltage for operation. This significantly reduces the risk of breakdown under low vacuum conditions, eliminating the need for additional vacuum isolation chambers or voltage divider structures. This avoids the drawbacks of conventional detectors like the CEM detector, which require high voltage and cannot operate normally in low-vacuum environments. Therefore, it solves the problem that both the quadrupole mass analyzer 6 and the detector 8 must be used in a high-vacuum environment. Furthermore, the filament 4 is placed in an independent high-vacuum environment, extending its lifespan, preventing oxidation, and improving the instrument's stability and durability.

[0021] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A high-sensitivity EIQ-MS mass spectrometry structure under low vacuum conditions, characterized in that, The system includes a sample inlet capillary (1), a first vacuum chamber (2), a second vacuum chamber (3), a filament (4), a reflective electrode (5), a quadrupole mass analyzer (6), a glass housing (7), and a detector (8). The sample inlet capillary (1) is located on the input side of the first vacuum chamber (2), and the first vacuum chamber (2) forms an ionization region (2a) located behind the sample inlet capillary (1). The quadrupole mass analyzer (6) and the detector (8) are sequentially arranged in the first vacuum chamber (2a) behind the ionization region (2a). 2) Inside, the glass shell (7) is wrapped around the quadrupole mass analyzer (6), the second vacuum chamber (3) is fitted and fixed to the outside of the first vacuum chamber (2), the filament (4) is arranged in the second vacuum chamber (3) above the ionization region (2a), the reflective electrode (5) is arranged in the second vacuum chamber (3) below the ionization region (2a), and small holes for electron beams to pass through are opened on the upper and lower side walls of the first vacuum chamber (2) corresponding to the ionization region (2a).

2. The high-sensitivity EIQ-MS mass spectrometry structure under low vacuum environment according to claim 1, characterized in that, A first focusing electrode (10) is provided between the filament (4) and the small hole on the side wall of the first vacuum chamber (2), and between the reflective electrode (5) and the small hole on the side wall of the first vacuum chamber (2).

3. A high-sensitivity EIQ-MS mass spectrometry structure under low vacuum conditions according to claim 1 or 2, characterized in that, A second focusing electrode (11) is also provided between the ionization region (2a) and the quadrupole mass analyzer (6).

4. A high-sensitivity EIQ-MS mass spectrometry structure under low vacuum conditions according to claim 1 or 2, characterized in that, The first vacuum chamber (2) and the second vacuum chamber (3) are kept at a constant vacuum level by continuous pumping by vacuum pump (9), and the pressure value of the first vacuum chamber (2) is one order of magnitude lower than the pressure value of the second vacuum chamber.

5. A high-sensitivity EIQ-MS mass spectrometry structure under low vacuum conditions according to claim 1 or 2, characterized in that, The voltage applied to the reflective electrode (5) is greater than the voltage applied to the filament (4).

6. A high-sensitivity EIQ-MS mass spectrometry structure under low vacuum conditions according to claim 1 or 2, characterized in that, The glass shell (7) is vacuum glass.

7. A high-sensitivity EIQ-MS mass spectrometry structure under low vacuum conditions according to claim 1 or 2, characterized in that, The detector (8) is an MCP detector.

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