Multi-stage vacuum system capable of respectively regulating pressure for mass spectrometer and application of multi-stage vacuum system

Abstract

The invention provides a multistage vacuum system capable of respectively regulating pressure for a mass spectrum, and belongs to the technical field of mass spectrometers. The device comprises a multi-stage vacuum cavity and a vacuum pump for vacuumizing the multi-stage vacuum cavity, the multi-stage vacuum cavity at least comprises a first-stage vacuum cavity body, a second-stage vacuum cavity body, a third-stage vacuum cavity body, a fourth-stage vacuum cavity body and a fifth-stage vacuum cavity body. The air pressure requirements of different structural units of the space tandem mass spectrometer can be met, and particularly, the requirements that the working air pressure range of the collision reaction tank is relatively high and the working air pressure of the mass analyzers on the two sides is relatively low are met simultaneously, so that the sample testing requirement in the total mass range is met, the instrument sensitivity is improved, and the cost is reduced. The interference in the test can be effectively removed, the test performance of an instrument is obviously improved, and trace or ultra-trace detection is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of mass spectrometers, and in particular to a multi-stage vacuum system capable of separately adjusting pressures for a mass spectrometer and an application thereof in a space tandem mass spectrometer. Background Art

[0002] A mass spectrometer is a chemical analysis instrument that analyzes and detects ions of different mass-to-charge ratios. Different mass spectrometers can be used to detect samples of different forms and characteristics, such as organic and inorganic. Ions are generally generated from the ion source at the front end of the mass spectrometer and are detected after reaching the detector through the ion transmission system. The traditional mass spectrometer vacuum system (such as Figure 1 As shown in the figure, although high sensitivity, wide dynamic range, and simultaneous determination of multiple elements / multiple ions can be achieved, for trace or ultra-trace detection, samples with complex matrices will have serious mass spectral interference, and one of the main methods to solve this problem is the spatial tandem mass spectrometer. The spatial tandem mass spectrometer can use collision reactions to remove impurity interference and achieve trace or ultra-trace element testing in complex matrices. In addition, the spatial tandem mass spectrometer can also achieve a variety of other test modes to meet different test needs.

[0003] There are many types of spatial tandem mass spectrometers. The most common one is the triple quadrupole mass spectrometer, which is composed of two quadrupole mass analyzers connected in series, with a collision reaction cell between the two. The collision reaction cell contains multi-stage ion guide rods, which can selectively attenuate potential interfering ions by pressurizing the collision gas or reaction gas, or fragment the target under the action of the collision gas. In MS / MS mode, both quadrupoles act as unit mass filters. This configuration can eliminate mass spectral interferences including isobaric and doubly charged interferences and polyatomic ion overlaps in inorganic mass spectrometry; in organic mass spectrometry, it can eliminate mass spectral interferences of other targets and fragment the target. However, while adding a quadrupole and a collision / reaction cell, it also introduces the risk of reduced ion transmission efficiency and high working pressure of the quadrupole mass analyzer and high working pressure of the detector, resulting in discharge. How to ensure that the collision reaction cell pressure is high, the mass analyzer and detector working pressure is low, and how to improve the transmission efficiency of the target ion is one of the design difficulties of the spatial tandem mass spectrometer.

[0004] At present, there are many studies on the design of three-stage vacuum structures, but there are few existing technologies for the design of adjustable pressure multi-stage vacuum systems, which is an important direction for improving the vacuum system of space tandem mass spectrometers. Summary of the invention

[0005] In view of this, in order to solve the technical problem that the existing vacuum systems of space tandem mass spectrometers are mostly three-stage vacuum structures and lack a multi-stage vacuum system with adjustable pressure, in the first aspect, the present invention provides a multi-stage vacuum system with separately adjustable pressure for mass spectrometry, which can meet the gas pressure requirements of different structural units of the space tandem mass spectrometer, especially the requirements of the higher working gas pressure range of the collision reaction cell and the lower working gas pressure of the mass analyzers on both sides thereof, thereby meeting the sample testing requirements of the full mass range, improving the sensitivity of the instrument, being able to effectively remove interference in the test, significantly improving the test performance of the instrument, and realizing trace or ultra-trace detection.

[0006] To achieve the above object, the present invention provides the following technical solutions: A multi-stage vacuum system with separately adjustable pressure for a mass spectrometer, comprising a multi-stage vacuum cavity and a vacuum pump for evacuating the multi-stage vacuum cavity; The multi-stage vacuum chamber at least includes the following chambers: The first stage vacuum chamber is used to extract ionized samples from the atmospheric pressure ion source; a second-stage vacuum chamber, in which an extraction and guiding device is arranged for extracting and guiding the ion beam transmitted from the first-stage vacuum chamber and transmitting it to a third-stage vacuum chamber; A third-stage vacuum chamber, in which a first-stage mass analyzer is arranged, for separating the ion beam transmitted from the second-stage vacuum chamber, and controlling the ion beam of a specific mass number to pass through the first-stage mass analyzer; A fourth-stage vacuum chamber is provided with a collision reaction pool for introducing collision gas or reaction gas to reduce interference in the ion beam transmitted from the third-stage vacuum chamber, or to obtain fragment information after fragmenting the target object; The fifth-stage vacuum chamber has a second-stage mass analyzer and a detector disposed therein. The second-stage mass analyzer is used to separate the ion beam transmitted through the fourth-stage vacuum chamber, and to control the ion beam of a specific mass number to pass through the second-stage mass analyzer and enter the detector, thereby obtaining a mass spectrum signal.

[0007] Preferably, the atmospheric pressure ion source comprises one of an ICP source, an APCI source and an ESI source.

[0008] Preferably, the working pressure in the first-stage vacuum chamber is 100 Pa to 1.013×10 5 Pa.

[0009] Preferably, the working gas pressure in the second-stage vacuum chamber is 0.01Pa to 10Pa.

[0010] Preferably, the working pressure in the third-stage vacuum chamber is 1×10 -5 Pa to 1×10-3 Pa.

[0011] Preferably, the working pressure in the fourth-stage vacuum chamber is 1×10 -3 Pa to 1×10 -1 Pa.

[0012] Preferably, the working pressure in the fifth-stage vacuum chamber is 1×10 -5 Pa to 1×10 -3 Pa.

[0013] Preferably, the extraction and guiding device is one of an electrostatic lens group, an ion funnel, an ion drift tube and a multipole guiding structure.

[0014] Preferably, the first-stage mass analyzer is a quadrupole mass analyzer or an ion trap mass analyzer.

[0015] Preferably, the collision reaction cell is used for inorganic mass spectrometry analysis or organic mass spectrometry analysis; a multipole or an ion trap is arranged inside the collision reaction cell.

[0016] Preferably, the second-stage mass analyzer comprises one of a quadrupole mass analyzer, an ion trap mass analyzer and a time-of-flight analyzer.

[0017] Preferably, the detector comprises one of a Faraday cup, a split dynode electron multiplier, a channel electron multiplier, a microchannel plate and a scintillation photomultiplier.

[0018] Preferably, the vacuum pump is a multi-stage vacuum pump.

[0019] Preferably, the multi-stage vacuum pump comprises at least a primary vacuum pump and a secondary vacuum pump connected to each other; The primary vacuum pump is a rotary oil-sealed pump, and the secondary vacuum pump is a molecular pump.

[0020] Preferably, the molecular pump is a single-port molecular pump and / or a multi-port molecular pump; The single-port molecular pump is used to evacuate a single vacuum chamber, and the multi-port molecular pump is used to evacuate multiple vacuum chambers.

[0021] Preferably, the multi-stage vacuum pump further includes a three-stage vacuum pump, and the three-stage vacuum pump is an ion pump.

[0022] Preferably, the aperture of the connecting hole between each stage of vacuum chambers is between 0.5-10 mm, and the working gas pressure in the vacuum chamber is adjusted by changing the pumping speed of the vacuum pump, the aperture size of the connecting hole and the intake gas flow rate.

[0023] Preferably, the multi-stage vacuum chamber is formed by a one-time molding process or assembled in stages.

[0024] In a second aspect, the present invention further provides the use of the above-mentioned multi-stage vacuum system with separately adjustable pressure for a mass spectrometer in a spatial tandem mass spectrometer.

[0025] Preferably, the spatial tandem mass spectrometer is an inductively coupled plasma triple quadrupole mass spectrometer.

[0026] Compared with the prior art, the present invention has the following beneficial effects: The multi-stage vacuum system with separately adjustable pressures for a mass spectrometer provided by the present invention can meet the pressure requirements of different structural units of a space tandem mass spectrometer and the pressure requirements of an inorganic / organic space tandem mass spectrometer through the design of a multi-stage vacuum cavity, and can flexibly adjust the working pressure of a specific cavity, especially to simultaneously meet the requirements of a higher working pressure range of a collision reaction cell in an MSn reaction and a lower working pressure of mass analyzers on both sides thereof, thereby meeting the requirements of sample testing in a full mass range, improving the sensitivity of the instrument, being able to effectively remove interference in the test, reducing background interference, allowing more target ions to enter the detector, effectively improving ion transmission efficiency, reducing background noise, significantly improving the test performance of the instrument, realizing trace or ultra-trace detection, and thus improving the sensitivity of the mass spectrometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 For the conventional mass spectrometer vacuum system, Figure 1 P1, P2 and P3 in the figure represent the first-stage vacuum chamber, the second-stage vacuum chamber and the third-stage vacuum chamber respectively, which is a three-stage vacuum system structure; Figure 2 Schematic diagram of a multi-stage vacuum system with separately adjustable pressure for a mass spectrometer of the present invention, wherein P1, P2, P3 and P4 correspond to the first stage vacuum chamber to the fourth stage vacuum chamber, P 5+N (N is an integer and ≥ 0) represents the fifth-level vacuum chamber and above; Figure 3 Schematic diagram of the first spatial tandem mass spectrometer with a five-stage vacuum system; Figure 4 is a schematic diagram of a second spatial tandem mass spectrometer with a five-stage vacuum system; Figure 5 It is the ion intensity diagram under different pore sizes; In the figure, 1. first-stage vacuum chamber; 2. second-stage vacuum chamber; 3. third-stage vacuum chamber; 4. fourth-stage vacuum chamber; 5. fifth-stage vacuum chamber; 6. single-port molecular pump; 7. double-port molecular pump; 8. vacuum pump; 9. extraction structure; 10. extraction guide device; 11. first-stage mass analyzer; 12. collision reaction cell; 13. second-stage mass analyzer; 14. detector. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] First, as Figure 2-5 As shown, a multi-stage vacuum system with separately adjustable pressure for a mass spectrometer comprises a multi-stage vacuum chamber and a vacuum pump 8 for evacuating the multi-stage vacuum chamber; The multi-stage vacuum chamber at least includes the following chambers: The first-stage vacuum chamber 1 is used to extract ionized samples from the atmospheric pressure ion source; The working pressure of the first-stage vacuum chamber 1 is preferably 100 Pa to 1.013×10 5 Pa (standard atmospheric pressure); The atmospheric pressure ion source preferably includes but is not limited to one of an ICP source, an APCI source and an ESI source, which can be selected according to actual needs and no special requirements are made therefor. The extraction structure 9 therein preferably selects a skimmer group in a mass spectrometer; A second-stage vacuum chamber 2 is provided with an extraction and guiding device 10 for extracting and guiding the ion beam transmitted from the first-stage vacuum chamber and transmitting it to a third-stage vacuum chamber; The working pressure of the second-stage vacuum chamber 2 is preferably 0.01Pa to 10Pa; A third-stage vacuum chamber 3 is provided with a first-stage mass analyzer 11 therein, which is used to separate the ion beam transmitted from the second-stage vacuum chamber and control the ion beam with a specific mass number to pass through the first-stage mass analyzer 11; The working pressure of the third-stage vacuum chamber 3 is preferably 1×10 -5 Pa to 1×10 -3 Pa; The fourth-stage vacuum chamber 4 is provided with a collision reaction pool 12 therein, which is used to introduce collision gas or reaction gas to reduce interference in the ion beam transmitted from the third-stage vacuum chamber, or to obtain fragment information after breaking up the target object. It is preferred that the introduction of collision gas or reaction gas does not affect the optimal working gas pressure of the front and rear-stage vacuum chambers; The working pressure in the fourth-stage vacuum chamber 4 is 1×10 -3 Pa to 1×10 -1 Pa; The fifth-stage vacuum chamber 5 is provided with a second-stage mass analyzer 13 and a detector 14, wherein the second-stage mass analyzer 13 is used to separate the ion beam transmitted through the fourth-stage vacuum chamber 4, and control the ion beam of a specific mass number to pass through the second-stage mass analyzer 13 and enter the detector 14, thereby obtaining a mass spectrum signal; The working pressure in the fifth vacuum chamber 5 is 1×10 -5 Pa to 1×10 -3 Pa.

[0032] In the present invention, the extraction and guiding device 10 includes but is not limited to one of an electrostatic lens group, an ion funnel, an ion drift tube and a multipole guiding structure, and can be selected according to actual needs.

[0033] In the present invention, the first-stage mass analyzer 11 includes but is not limited to a quadrupole mass analyzer or an ion trap mass analyzer, and can be selected according to actual needs.

[0034] In the present invention, the collision reaction cell 12 is used for inorganic mass spectrometry analysis or organic mass spectrometry analysis; a multipole or an ion trap is arranged inside the collision reaction cell 12, which can be selected according to actual needs, wherein the multipole is preferably a hexapole.

[0035] In the present invention, the second-stage mass analyzer 13 includes but is not limited to one of a quadrupole mass analyzer, an ion trap mass analyzer and a time-of-flight analyzer, and can be selected according to actual needs.

[0036] In the present invention, the detector includes but is not limited to one of a Faraday cup, a split dynode electron multiplier, a channel electron multiplier, a microchannel plate and a scintillation photomultiplier.

[0037] The present invention merely exemplifies the vacuum system of the five-stage vacuum chamber. Those skilled in the art may also select a vacuum system with more than five stages, such as seven stages, nine stages, etc., according to actual needs.

[0038] Each vacuum chamber preferably has an air inlet and an air outlet. The working air pressure in the target vacuum chamber is adjusted by controlling the air inlet flow rate, adjusting the aperture size of the connecting holes between chambers, changing the pumping speed of the vacuum pump 8, etc. When the system has more vacuum levels (more than five levels), the added intermediate vacuum chamber generally contains the nth-level focusing guide device, or the nth-level mass analyzer, or the nth-level collision reaction pool, but the detector 14 is always set in the last-level vacuum chamber. The multi-level vacuum chambers are connected by micropores, grids, or slits in combination with sealing rings. Except for the first-level vacuum chamber, the other vacuum chambers need to be connected to the vacuum pump 8 to control the vacuum degree of each chamber separately.

[0039] It should be noted that the optimal working gas pressure may be different for samples under different reaction gases and needs to be adjusted according to actual conditions.

[0040] In summary, the present invention can meet the gas pressure requirements of different structural units of the spatial tandem mass spectrometer through the design of a multi-stage vacuum chamber, especially the requirements of a higher working gas pressure range of the collision / reaction cell in the MSn reaction and a lower working gas pressure of the mass analyzers on both sides thereof, thereby meeting the sample testing requirements of the full mass range, improving the sensitivity of the instrument, effectively removing interference in the test, significantly improving the test performance of the instrument, and realizing trace or ultra-trace detection.

[0041] In the present invention, the vacuum pump 8 is a multi-stage vacuum pump, such as two stages or more.

[0042] In the present invention, the multi-stage vacuum pump comprises at least a primary vacuum pump and a secondary vacuum pump which are connected to each other; The primary vacuum pump includes but is not limited to a rotary oil-sealed pump, and the secondary vacuum pump includes but is not limited to a molecular pump.

[0043] Preferably, the molecular pump is a single-port molecular pump 6 and / or a multi-port molecular pump; The single-port molecular pump 6 is used to evacuate a single vacuum cavity, and the multi-port molecular pump is used to evacuate multiple vacuum cavities. It should be noted that the multi-port molecular pump has the ability to individually control the vacuum pumping speed of each port. The single-port molecular pump 6 is preferably used to evacuate any level of vacuum cavity. The first-level vacuum cavity does not need to be directly evacuated using the single-port molecular pump 6, and only needs to be evacuated by the primary vacuum pump.

[0044] For example, the vacuum system uses a two-stage vacuum pump, the primary vacuum pump is a rotary oil-sealed pump, the secondary vacuum pump includes two single-port molecular pumps 6, a double-port molecular pump 7 is used between the second-stage vacuum cavity and the third-stage vacuum cavity, and the two single-port molecular pumps 6 evacuate the fourth-stage vacuum cavity and the fifth-stage vacuum cavity respectively, thereby achieving the purpose of cost saving.

[0045] In the present invention, the multi-stage vacuum pump further includes a three-stage vacuum pump, and the three-stage vacuum pump is an ion pump.

[0046] In the present invention, each stage of vacuum cavity can independently control the pumping speed of the molecular pump, each stage of vacuum cavity is connected through a connecting hole, the aperture of the connecting hole between each stage of vacuum cavity is between 0.5-10 mm, and the working gas pressure in the vacuum cavity is adjusted by changing the pumping speed of the vacuum pump, the aperture of the connecting hole and the air inlet flow rate.

[0047] In the present invention, the multi-stage vacuum chamber adopts a one-time molding process or a staged assembly.

[0048] The working principle of the above-mentioned multi-stage vacuum system with separately adjustable pressure for mass spectrometer provided by the present invention is as follows: First, the extraction structure 9 (skimmer group in the mass spectrometer) inside the first-stage vacuum chamber is used to extract ions from the atmospheric pressure ion source; the extraction guide device 10 inside the second-stage vacuum chamber transmits and cools the charged ions and removes neutral ions; the first mass analyzer inside the third-stage vacuum chamber further extracts the analysis ions; the fourth-stage vacuum chamber uses the collision reaction cell 12 to remove interfering ions; the second mass analyzer inside the fifth-stage vacuum chamber extracts ions and transmits them to the detector 14, thereby completing the entire analysis process.

[0049] Secondly, the cavity where the collision reaction pool 12 is located requires a higher working gas pressure, while the mass analyzers on both sides require a lower working gas pressure. The present invention can adjust the gas pressure of the target cavity by changing the molecular pumping speed, the size of the connecting aperture between cavities, and controlling the inlet gas flow rate.

[0050] Finally, after actual verification on a triple-quadruple experimental platform, the present invention found that different gas pressures in the collision cell do affect the reaction efficiency, thereby affecting the noise intensity; the working gas pressure of the mass analyzer does affect the signal intensity and resolution. Adjusting the different levels of the cavity to the appropriate gas pressure can obtain better test results without affecting the quality of the mass analyzer.

[0051] In a second aspect, the present invention further provides the use of the above-mentioned multi-stage vacuum system with separately adjustable pressure for a mass spectrometer in a spatial tandem mass spectrometer.

[0052] In the present invention, the spatial tandem mass spectrometer is an inductively coupled plasma triple quadrupole mass spectrometer.

[0053] The technical solution of the present invention is clearly described in detail below in conjunction with specific embodiments.

[0054] Example 1

[0055] Embodiment 1 of the present invention, using Figure 4 The vacuum system shown in the figure builds a triple quadrupole experimental platform. The diameters of the different connecting holes between the fourth-stage vacuum chamber and the fifth-stage vacuum chamber are adjusted to 1 mm and 5 mm, and each molecular pump is kept pumping at full speed. Oxygen is introduced into the fourth-stage vacuum chamber as the collision reaction gas, and the flow rate is constant at 5 ml / min. Test the target in a complex matrix 111 Cd (Cd in 100ppm Mo solution, 10ppb), interferents are 95 Mo 16 O. When the aperture of the connecting hole between the two vacuum chambers was changed from 1 mm to 5 mm, and oxygen was introduced for 10 min, the vacuum value of the fifth vacuum chamber increased from 1.6×10 -5 Pa rises to 1.6×10 -4 Pa, as the vacuum in the vacuum chamber where the last-stage mass analyzer is located rises, the target 111 The Cd signal intensity decreased from 6000 to 1000. The interferences under the two experimental conditions 95 Mo 16 The intensity of O is basically 0~20cps, which proves that the triple quadrupole vacuum system has the function of removing interference, and the gas pressure of the fifth-stage vacuum chamber significantly affects the signal intensity of the target analyte.

[0056] Example 2 use Figure 4 The triple quadrupole experimental platform built by the vacuum system shown in the figure keeps the molecular pumps pumping at a constant speed. The aperture of the connecting hole between the third vacuum chamber and the fourth vacuum chamber is a fixed value between 1-5mm, and the aperture of the connecting hole between the fourth vacuum chamber and the fifth vacuum chamber is a fixed value between 1-5mm. Oxygen is introduced into the fourth vacuum chamber as a collision reaction gas, and the oxygen flow rate is adjusted from 0 to 5 ml / min to test the target in the complex matrix. 111 Cd (Cd in 100ppm Mo solution, 10ppb), interferents are 95 Mo 16 O. As the oxygen flow rate increases, the interference 95 Mo 16 The O intensity gradually decreases and reaches 0~20cps after a certain critical value. The vacuum value of the third-stage vacuum chamber is 1.6×10 -4Pa, the fifth stage vacuum chamber pressure is 2×10 -5 Pa, which meets the working pressure condition of quadrupole mass analyzer.

[0057] The diameters of the connecting holes between the third and fourth vacuum chambers of the platform were adjusted to 1 mm and 4 mm, and the molecular pumps were kept pumping at a constant speed. Oxygen was introduced into the fourth vacuum chamber as the collision reaction gas, and the flow rate was constant at 2 ml / min. When the connecting hole diameter between the two vacuum chambers was increased from 1 mm to 4 mm, the vacuum value of the third vacuum chamber increased from 1.2×10 -4 Pa to 1.7×10 -4 Pa, the change is not significant; the working pressure of the fourth-stage vacuum chamber is 1.7×10 -2 Pa dropped to 1.2×10 -3 Pa, the fifth-stage vacuum chamber is always 2×10 -5 Pa. At different apertures, the interference 95 Mo 16 O and analyte 111 Cd to evaluate, interference 95 Mo 16 The intensity of O is between 0 and 20 cps, proving that the triple four-stage vacuum system has the function of removing interference.

[0058] like Figure 5 As shown in the figure, the intensity values ​​of Be, In, and U at 1 ppb concentration under four groups of apertures are compared. As the aperture increases, the signal intensity tends to increase, which may be related to the diameter of the ion transmission channel. Without affecting the working pressure of the adjacent vacuum chamber, a design with a large aperture should be selected as much as possible to improve the ion transmission efficiency.

[0059] The above are only preferred specific implementations of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and improved concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A multi-stage vacuum system with separately adjustable pressure for a mass spectrometer, characterized in that: It comprises a multi-stage vacuum chamber and a vacuum pump for evacuating the multi-stage vacuum chamber; The multi-stage vacuum chamber at least includes the following chambers: The first stage vacuum chamber is used to extract ionized samples from the atmospheric pressure ion source; a second-stage vacuum chamber, in which an extraction and guiding device is arranged for extracting and guiding the ion beam transmitted from the first-stage vacuum chamber and transmitting it to a third-stage vacuum chamber; A third-stage vacuum chamber, in which a first-stage mass analyzer is arranged, for separating the ion beam transmitted from the second-stage vacuum chamber, and controlling the ion beam of a specific mass number to pass through the first-stage mass analyzer; A fourth-stage vacuum chamber is provided with a collision reaction pool for introducing collision gas or reaction gas to reduce interference in the ion beam transmitted from the third-stage vacuum chamber, or to obtain fragment information after fragmenting the target object; a fifth-stage vacuum chamber, in which a second-stage mass analyzer and a detector are arranged, wherein the second-stage mass analyzer is used to separate the ion beam transmitted through the fourth-stage vacuum chamber, and control the ion beam of a specific mass number to pass through the second-stage mass analyzer and enter the detector, thereby obtaining a mass spectrum signal; Preferably, the atmospheric pressure ion source comprises one of an ICP source, an APCI source and an ESI source; Preferably, the working pressure in the first-stage vacuum chamber is 100 Pa to 1.013×10 5 Pa; Preferably, the working gas pressure in the second-stage vacuum chamber is 0.01Pa to 10Pa; Preferably, the working pressure in the third-stage vacuum chamber is 1×10 -5 Pa to 1×10 -3 Pa; Preferably, the working pressure in the fourth-stage vacuum chamber is 1×10 -3 Pa to 1×10 -1 Pa; Preferably, the working pressure in the fifth-stage vacuum chamber is 1×10 -5 Pa to 1×10 -3 Pa; Preferably, the extraction and guiding device is one of an electrostatic lens group, an ion funnel, an ion drift tube and a multipole guiding structure.

2. A multi-stage vacuum system with separately adjustable pressure for a mass spectrometer according to claim 1, characterized in that: The first-stage mass analyzer is a quadrupole mass analyzer or an ion trap mass analyzer.

3. The multi-stage vacuum system with separately adjustable pressure for mass spectrometer according to claim 1, characterized in that: The collision reaction cell is used for inorganic mass spectrometry analysis or organic mass spectrometry analysis; a multipole or an ion trap is arranged inside the collision reaction cell.

4. The multi-stage vacuum system with separately adjustable pressure for mass spectrometer according to claim 1, characterized in that: The second-stage mass analyzer includes one of a quadrupole mass analyzer, an ion trap mass analyzer and a time-of-flight analyzer.

5. The multi-stage vacuum system with separately adjustable pressure for mass spectrometer according to claim 1, characterized in that: The detector includes one of a Faraday cup, a split dynode electron multiplier, a channel electron multiplier, a microchannel plate and a scintillation photomultiplier.

6. The multi-stage vacuum system with separately adjustable pressure for mass spectrometer according to claim 1, characterized in that: The vacuum pump is a multi-stage vacuum pump; Preferably, the multi-stage vacuum pump comprises at least a primary vacuum pump and a secondary vacuum pump connected to each other; The primary vacuum pump is a rotary oil-sealed pump, and the secondary vacuum pump is a molecular pump; Preferably, the molecular pump is a single-port molecular pump and / or a multi-port molecular pump; The single-port molecular pump is used to evacuate a single vacuum chamber, and the multi-port molecular pump is used to evacuate multiple vacuum chambers; Preferably, the multi-stage vacuum pump further includes a three-stage vacuum pump, and the three-stage vacuum pump is an ion pump.

7. The multi-stage vacuum system with separately adjustable pressure for mass spectrometer according to claim 1, characterized in that: The aperture of the connecting hole between each level of vacuum chamber is between 0.5-10 mm, and the working gas pressure in the vacuum chamber is adjusted by changing the pumping speed of the vacuum pump, the aperture size of the connecting hole and the inlet gas flow rate.

8. A multi-stage vacuum system with separately adjustable pressure for a mass spectrometer according to any one of claims 1 to 7, characterized in that: The multi-stage vacuum chamber adopts a one-time molding process or a staged assembly.

9. Use of a multi-stage vacuum system with separately adjustable pressure for a mass spectrometer according to any one of claims 1 to 8 in a spatial tandem mass spectrometer.

10. The use according to claim 9, characterized in that: The spatial tandem mass spectrometer is an inductively coupled plasma triple quadrupole mass spectrometer.

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