Chemical ionization-differential electromobility screening-mass spectrometry combined system and working method

Abstract

The invention discloses a chemical ionization-differential electromobility screening-mass spectrometry combined system and a working method, and belongs to the technical field of molecular cluster measurement, the chemical ionization-differential electromobility screening-mass spectrometry combined system comprises a normal pressure chemical ionization source system, a planar differential electromobility analyzer, a sheath gas circulation system, an ion transmission interface, an aerosol electrometer, a mass spectrometer and a control system; the chemical ionization source system is connected with the planar differential electromobility analyzer, the planar differential electromobility analyzer and the sheath gas circulation system form a circulation gas path, and the planar differential electromobility analyzer transmits sample ions to be detected to the aerosol electrometer and the mass spectrometer for detection through a special ion transmission interface; the control system is connected with the normal-pressure chemical ionization source system, the planar differential electromobility analyzer, the sheath gas circulation system of the planar differential electromobility analyzer and the mass spectrometer, and provides high voltage and data acquisition, storage and reading. According to the invention, efficient on-line in-situ synchronous monitoring of chemical components and electromobility of gas / molecular clusters in a gas phase can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of molecular cluster measurement, and particularly relates to a chemical ionization-differential mobility spectrometry-mass spectrometry combined system and a working method. Background Art

[0002] Chemical ionization (CI) is a soft ionization technique that realizes sample ionization through the principle of reaction between reagent ions and sample molecules, and is widely used in mass spectrometry technology. Chemical ionization atmospheric pressure interface time-of-flight mass spectrometry (CI-APi-ToF) has been applied to the real-time online measurement of various trace gases, molecular clusters, and aerosol particle chemical components in ambient air through chemical ionization methods. A differential mobility analyzer (DMA) can measure the true mobility and convert it into particle size. Coupling the front end with an ionization source can ionize aerosols and efficiently screen target charged particles. Further, when combined with a mass spectrometer (DMA-MS), it has the ability to synchronously measure the aerosol structure and chemical components. However, existing DMA-MS is only applicable to detecting clusters generated by electrospray or electrospray secondary ionization, lacking an in-situ ionization technique for gas-phase molecules and clusters that can be coupled with DMA-MS. Therefore, it is of great significance to develop an ionization source that can be coupled with DMA and a tandem mass spectrometer to achieve online in-situ measurement of environmental samples.

[0003] Atmospheric pressure chemical ionization sources based on various chemical reagents coupled with mass spectrometers have been widely used for the monitoring of gas and nano-aerosol sample molecules. Selecting an atmospheric pressure chemical ionization source coupled with a planar DMA and a tandem mass spectrometer can directly perform online in-situ monitoring of the structure and chemical components of gas-phase samples without any front-end treatment, and accurately identify the specific process of gaseous precursors growing into molecular clusters and even aerosols. Currently, there is no combined device based on an atmospheric pressure chemical ionization source coupled with a planar DMA in China.

[0004] Among the invention patents published in China, the patent with the authorization announcement number CN105632870A relates to an atmospheric pressure chemical ionization source for mass spectrometry. The designed atmospheric pressure chemical ionization source of this patent can provide pure product ions, and coupling with a mass spectrometer can realize the online detection of the chemical components and concentration of the sample to be measured, but it cannot obtain the structural characteristic information of the sample synchronously. The patent with the authorization announcement number CN113484402A relates to a planar differential mobility analyzer-mass spectrometer combined system based on an electrospray ionization source. The ion source adopted in this patent ionizes the sample with a liquid reagent, and is prone to dissolution or extraction effects during the ionization of gas molecules and clusters. Moreover, the charging efficiency of this device is low and it is not suitable for in-situ measurement of ambient air samples. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a chemical ionization-differential mobility spectrometry-mass spectrometry combined system and a working method.

[0006] To achieve the above object, the specific technical solution adopted by the present invention is as follows: A chemical ionization-differential mobility spectrometry-mass spectrometry combined system includes: an atmospheric pressure chemical ionization source system, a planar differential mobility analyzer, a sheath gas circulation system for providing sheath gas for the planar differential mobility analyzer, an ion transfer interface, an aerosol electrometer, and a mass spectrometer;

[0007] The atmospheric pressure chemical ionization source system includes a chemical ionization source main system, an ionization source for converting reagent vapor into reagent ions, a power supply box for continuously supplying power to the ionization source, and a gas source; an air inlet is provided at the side end of the chemical ionization source main system, and the air inlet is connected to the gas source through an air inlet pipe, and the gas source is used to provide sheath gas and reagent vapor; an air outlet is also provided at the side end of the chemical ionization source main system, and the air outlet is successively connected to a reagent nebulizer, a particulate filter, and a first suction pump through an air outlet pipe for discharging tail gas; a first sample outlet is provided at the rear end of the chemical ionization source main system, and the first sample outlet is connected to the planar differential mobility analyzer; a first sample inlet is provided at the front end of the chemical ionization source main system, and the first sample inlet is used to input a sample;

[0008] The planar differential mobility analyzer is connected to the front interface of the ion transfer interface through a second sample outlet; the ion transfer interface also has a rear interface and a side interface, which are respectively used to connect to the mass spectrometer and the aerosol electrometer;

[0009] The air outlet of the aerosol electrometer is successively provided with a flow limiting valve and a second suction pump, and the second suction pump is used to suck the sample from the first sample outlet of the chemical ionization source main system into the planar differential mobility analyzer and then into the aerosol electrometer.

[0010] Further, the gas source is respectively connected to the air inlet at the side end of the chemical ionization source main system through a first air inlet pipe and a second air inlet pipe; a first flow controller is provided on the first air inlet pipe for adjusting the sheath gas flow rate; a second flow controller and a reagent storage are provided on the second air inlet pipe, the reagent storage is used to store chemical reagents, the chemical reagents are blown off by the carrier gas provided by the gas source to generate reagent vapor, and the second flow controller is used to adjust the reagent vapor flow rate; a third flow controller is provided between the particulate filter and the first suction pump for adjusting the tail gas flow rate.

[0011] Further, the chemical ionization source main system includes an ion reaction chamber, a fixing module, and a transmission lens;

[0012] The fixing module is nested outside the ion reaction chamber for fixing the ionization source;

[0013] The transmission lens is embedded on the surface of the fixed module, and is used to enable the ionization source to project through the lens to the ion reaction chamber to convert the reagent vapor into reagent ions, and fully collide with the sample to be measured to generate sample ions to be measured;

[0014] The ion reaction chamber is a conical cylindrical body, and the radial dimension of its barrel is designed with variable diameter to specifically match the second sampling port of the planar differential mobility analyzer. A repulsion electrode and an acceleration electrode are arranged inside the reaction chamber, and are respectively connected to the chemical ionization source voltage controller through high-voltage power lines, and are used to control the voltage to generate electric fields of different magnitudes, so that the sample ions obtain a velocity parallel to the direction of the electric field and are guided to the first sampling port.

[0015] Further, the chemical ionization source main system includes an insect-proof net.

[0016] Further, the planar differential mobility analyzer adopts a special working mode with reverse electrode configuration, the upper electrode plate is grounded, and the lower electrode plate is connected to the high-voltage power line to generate an electric field between the two electrode plates; the sample ions enter from the second sampling port of the planar differential mobility analyzer, and under the combined action of the electric field and the sheath gas laminar flow provided by the sheath gas circulation system, the sample ions with specific mobility flow out from the second sampling port to realize the screening of the sample ions.

[0017] Further, the ion transfer interface body is specially connected by an insulating backing plate and a support housing. The other side of the insulating backing plate is closely attached to the lower electrode plate of the planar differential mobility analyzer; product ion through holes are provided in the middle of the support housing and the insulating backing plate, and a straight first electrostatic dissipation material tube is filled inside the through holes, so as to ensure that no electrostatic accumulation occurs inside the through holes on the premise of forming an insulating space between the lower electrode plate and the mass spectrometer, and form a sealed charged sample transfer channel when connected to the mass spectrometer; a second electrostatic dissipation material tube is provided at the side interface of the ion transfer interface and is connected to the inlet of the aerosol electrometer for transmitting charged sample ions.

[0018] Further, the system includes a control system, and the control system is respectively connected to the atmospheric pressure chemical ionization source system, the planar differential mobility analyzer, the sheath gas circulation system, the aerosol electrometer and the mass spectrometer through data lines, and is used to control the voltage and flow rate inside the atmospheric pressure chemical ionization source system, the switch of the planar differential mobility analyzer and the positive / negative high-voltage change, the flow rate of the sheath gas circulation system, and collect the data information of the planar differential mobility analyzer, the aerosol electrometer and the mass spectrometer, monitor the operation status of the system in real time, and store and read the corresponding data.

[0019] The present invention also provides a working method of a chemical ionization-differential mobility screening-mass spectrometry combined system, including the following steps:

[0020] The gas source continuously provides sufficient, dry and clean gas; the control system adjusts the inlet and outlet gas flow rates of the chemical ionization source main system and the sample injection flow rate of the first sample injection port by controlling three flow controllers; meanwhile, the chemical ionization source voltage controller applies different voltages to the repeller electrode and the acceleration electrode through the high-voltage power line to obtain an electric field; the control system displays the ionization source flow rate and the actual parameters of the electrodes in real time.

[0021] The control system controls the voltage of the lower electrode plate of the planar differential mobility analyzer and the flow rate of the sheath gas circulation system, and reads and stores in real time the screening voltage of the planar differential mobility analyzer, the voltage of the aerosol electrometer, the signal of the mass spectrometer, and the acquisition time corresponding to each data.

[0022] The control system can set two modes: fixed voltage mode and scanning voltage mode. In the fixed voltage mode, the voltage of the lower electrode plate is controlled to be a constant value, and the planar differential mobility analyzer screens the target samples with corresponding mobilities at this specific voltage. In the scanning voltage mode, the initial voltage, the termination voltage, and the voltage step are set for the lower electrode plate respectively, and the planar differential mobility analyzer scans sequentially at the established voltage step within the set voltage range for mobility screening.

[0023] In the fixed voltage mode, the control system synchronously reads the mass spectrometer data, statistically averages the mass spectrometry data according to the preset time resolution until the system stops running. In the scanning voltage mode, the control system extracts the mass spectrometer data corresponding to the corresponding time period according to the read screening voltage and its residence time, unifies the time reference of the whole set of systems to match the mobility data, repeats the voltage scanning program of the planar differential mobility analyzer, and statistically averages the obtained mass spectrometry data until the chemical ionization-differential mobility screening-mass spectrometry combined system stops running.

[0024] The beneficial effects of the present invention compared with the prior art are as follows: By adopting the chemical ionization-differential mobility screening-mass spectrometry combined system, the atmospheric pressure chemical ionization source can prevent the loss of smaller molecular clusters, avoid the extraction of organic substances in particulate matter by reagent ions, and the planar differential mobility analyzer has high transmission efficiency and screening resolution. The combination of the two can directly perform in-situ ionization and high-efficiency screening on environmental samples, and is connected with a mass spectrometer to realize the on-line in-situ synchronous measurement of the chemical components and mobilities of gases / molecular clusters in the real atmospheric environment. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0026] Figure 1 It is a schematic structural diagram of the system described in the present invention;

[0027] Figure 2 It is a schematic diagram of the internal sample route of the system where the atmospheric pressure chemical ionization source main system of the system described in the present invention is combined with a planar differential mobility analyzer and a mass spectrometer;

[0028] Figure 3 It is an ion transport efficiency diagram when the sample combines with a special ion transport interface under a specific reverse power connection mode of the planar differential mobility analyzer;

[0029] In the figure, the atmospheric pressure chemical ionization source system 1, the planar differential mobility analyzer 2, the sheath gas circulation system 3, the control system 4, the ion transport interface 5, the aerosol electrometer 6, the flow limiting valve 7, the second air pump 8, the mass spectrometer 9, the chemical ionization source main system 10, the ionization source 11, the power supply box 12, the gas source 13, the first flow controller 14, the reagent storage 15, the second flow controller 16, the reagent dissolver 17, the particulate filter 18, the third flow controller 19, the first air pump 20, the chemical ionization source voltage controller 21, the high voltage power line 22, the first sample inlet 23, the air inlet 24, the insect screen 25, the fixing module 26, the transmission lens 27, the ion reaction chamber 28, the repulsion electrode 29, the acceleration electrode 30, the air outlet 31, the upper electrode plate 32, the lower electrode plate 33, the insulating backing plate 34, the support housing 35, the first electrostatic dissipation material tube 36, the second electrostatic dissipation material tube 37. Detailed implementation manners

[0030] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present invention. On the contrary, they are merely examples of the devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0031] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the present invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0032] It should be understood that although the terms first, second, third, etc. may be used in the present invention to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to a determination".

[0033] The present invention will be described in detail below with reference to the accompanying drawings. Without conflict, the features in the following embodiments and implementation manners may be combined with each other.

[0034] An embodiment of the present invention provides a chemical ionization-differential mobility spectrometry-mass spectrometry combined system and a working method. The environmental sample is efficiently ionized by a chemical ionization source, and a planar differential mobility analyzer is coupled to achieve high-resolution screening of the electrophoretic mobility of charged products. Connecting with a mass spectrometer can synchronously measure the chemical components and particle size structure of charged target substances.

[0035] As Figure 1 shown, the main configurations of the present invention include an atmospheric pressure chemical ionization source system 1, a planar differential mobility analyzer 2, a sheath gas circulation system 3, a control system 4, an ion transfer interface 5, an aerosol electrometer 6, and a mass spectrometer 9. The internal sample roadmap of the main part of the system of the present invention, that is, the atmospheric pressure chemical ionization source system 1 in combination with the planar differential mobility analyzer 2 and the mass spectrometer 9, is as Figure 2 shown.

[0036] The atmospheric pressure chemical ionization source system 1 is cooperatively connected with the planar differential mobility analyzer 2. The sheath gas circulation system 3 provides a clean sheath gas circulation path for the planar differential mobility analyzer 2. The planar differential mobility analyzer 2 is connected to the ion transfer interface 5. The ion transfer interface 5 is also provided with a reverse interface and a side interface, which are used to connect the mass spectrometer 9 and the aerosol electrometer 6 respectively. The air outlet of the aerosol electrometer 6 is sequentially connected to a flow limiting valve 7 and a second suction pump 8. The control system 4 is connected to the atmospheric pressure chemical ionization source system 1, the planar differential mobility analyzer 2, the sheath gas circulation system 3, the aerosol electrometer 6, and the mass spectrometer 9 through data lines, and is used to control the internal voltage and flow rate of the atmospheric pressure chemical ionization source system 1, the switch and positive / negative high voltage change of the planar differential mobility analyzer 2, and the flow rate of the sheath gas circulation system 3, and to monitor the operation status of the system in real time, and store / read corresponding data.

[0037] The atmospheric pressure chemical ionization source system 1 mainly includes: a chemical ionization source main system 10, an ionization source 11 for converting reagent vapor into reagent ions, a power supply box 12 for continuously supplying power to the ionization source 11, a gas source 13, a reagent reservoir 15, a reagent dissolver 17, a particulate filter 18, and a first suction pump 20; the side end of the chemical ionization source main system 10 is provided with an air inlet 24 and an air outlet 31, the front end is provided with a first sample inlet 23, and the rear end is provided with a first sample outlet; the gas source 13 supplies gas to the system through a first gas pipe and a second gas pipe. The first gas pipe is controlled by a first flow controller 14 to provide clean sheath gas, and the second gas pipe is controlled by a second flow controller 16 to provide carrier gas to blow out the chemical reagent in the reagent reservoir 15 to generate reagent vapor. The first gas pipe and the second gas pipe enter through the air inlet 24 of the chemical ionization source main system 10 together through a tee joint. The tail gas passes through the reagent dissolver 17 and the particulate filter 18 and is sucked out by the first suction pump 20. The total flow rate is controlled by a third flow controller 19.

[0038] The chemical ionization source main system 10 further includes an insect-proof net 25, a fixing module 26, a transmission lens 27, and an ion reaction chamber 28. The ion reaction chamber 28 adopts a special cylinder structure with gradually reduced radial dimensions to adapt to the planar differential mobility analyzer 2. At the same time, the system and its air intake configuration are optimized according to the size variation of the cylinder body to ensure that the sample and the sheath gas maintain a gas flow balance to form a stable laminar flow after entering the system. By adding a repulsion electrode 29 and an acceleration electrode 30 to the inside of the system, it is more conducive to the focusing and movement of sample ions inside the conical reaction chamber with a variable diameter design. The sample to be measured enters through the first sample inlet 23 and moves towards the ion reaction chamber 28. The fixing module 26 is nested outside the ion reaction chamber 28 to fix the ionization source 11. The transmission lens 27 is embedded on the surface of the fixing module 26, allowing the ionization source 11 to project through the lens to the ion reaction chamber 28 to convert the reagent vapor into reagent ions, and fully collide and react with the sample to be measured to generate sample ions to be measured. The power supply box 12 continuously supplies power to the ionization source 11 to ensure continuous operation. The chemical ionization source voltage controller 21 applies different voltages to the repulsion electrode 29 and the acceleration electrode 30 through a high-voltage power line 22 to generate an electric field, so that the sample ions are focused and obtain a velocity parallel to the direction of the electric field. At the same time, under the action of the electric field force, the sample flow, and the mixed gas flow of the sheath gas and the reagent vapor, they move smoothly along the preset movement trajectory towards the first sample outlet, ensuring that the sample ions are introduced into the planar differential mobility analyzer 2 accurately and efficiently in the best state.

[0039] The sample ions to be measured generated by the chemical ionization source main system 10 are sucked out from the first sample outlet under the pumping force of the second pumping pump 8. At the same time, the planar differential mobility analyzer 2 adopts a special working mode with a reverse electrode configuration, where the upper electrode plate 32 is grounded and the lower electrode plate 33 is connected to the high-voltage power supply line to ensure the effective transmission of the sample ions ionized by the chemical ionization source main system 10 to the second sample inlet of the planar differential mobility analyzer 2. The control system 4 controls the on / off of the voltage and sets the voltage range to generate an electric field between the two electrode plates; the clean sheath gas generated by the sheath gas circulation system 3 has its flow rate controlled by the control system 4 and enters from the upper end of the planar differential mobility analyzer 2 and flows out from the lower end; the sample ions enter from the pores of the upper electrode plate 32 and are under the combined action of the sheath gas laminar flow and the electric field. The sample ions with specific particle sizes flow out from the pores of the lower electrode plate 33 to achieve sample screening, and then lead to the ion transfer interface 5.

[0040] The main body of the ion transfer interface 5 is specially connected by an insulating backing plate 34 and a support housing 35 to specifically adapt to the connection between the planar differential mobility analyzer 2 and the mass spectrometer 9 under a specific reverse electrode working mode; the other side of the insulating backing plate 34 is closely attached to the lower electrode plate 33 of the planar differential mobility analyzer 2; product ion through holes are provided in the middle of both the support housing 35 and the insulating backing plate 34, and the inside is filled with a straight first electrostatic dissipation material tube 36 to ensure the smooth flight of ions along the pipeline and prevent ion loss, so as to ensure that no electrostatic accumulation occurs inside the through hole on the premise of forming an insulating space between the lower electrode plate 33 and the mass spectrometer 9. The connection between the first electrostatic dissipation material tube 36 and the mass spectrometer 9 can form a sealed charged sample transmission channel with high transfer efficiency; another interface is provided on the side of the ion transfer interface 5, and a straight second electrostatic dissipation material tube 37 is connected to the air inlet of the aerosol electrometer 6. The pumping force of the second pumping pump 8 sucks some charged sample ions to the aerosol electrometer 6; the sample ions screened by the planar differential mobility analyzer 2 flow out from the lower electrode plate 33 and are simultaneously transmitted to the aerosol electrometer 6 and the mass spectrometer 9 for detection through the special ion transfer interface 5. The control system 4 reads and collects in real time the screening voltage and sample ion signal of the planar differential mobility analyzer 2, the voltage of the aerosol electrometer 6, and the mass-to-charge ratio and signal of the mass spectrometer 9.

[0041] The gas source 13 continuously provides sufficient, dry, and clean gas; the control system 4 adjusts the flow rates of the inlet 24 and outlet 31 of the chemical ionization source main system 10 and the sampling flow rate of the first sampling port 23 by controlling three flow controllers; meanwhile, the chemical ionization source voltage controller 21 applies different voltages to the repeller electrode 29 and the acceleration electrode 30 through the high-voltage power line 22 to obtain an electric field; the control system 4 displays the ionization source flow rate and the actual parameters of the electrodes in real time. The control system 4 controls the voltage of the lower electrode plate 33 of the planar differential mobility analyzer 2 and the flow rate of the sheath gas circulation system 3, and reads and stores in real time the screening voltage of the planar differential mobility analyzer 2, the voltage of the aerosol electrometer 6, the signal of the mass spectrometer 9, and the acquisition time corresponding to each data. The control system 4 can set two modes: the fixed voltage mode and the scanning voltage mode. In the fixed voltage mode, the voltage of the lower electrode plate 33 is controlled to be a constant value, and the planar differential mobility analyzer 2 screens the target samples with corresponding mobilities at this specific voltage; in the scanning voltage mode, the initial voltage, the termination voltage, and the voltage step are set for the lower electrode plate 33 respectively, and the planar differential mobility analyzer 2 scans in sequence according to the established voltage step within the set voltage range for mobility screening. In the fixed voltage mode, the control system 4 synchronously reads the data of the mass spectrometer 9, statistically averages the mass spectrometry data according to the preset time resolution until the system stops running; in the scanning voltage mode, the control system 4 extracts the data of the mass spectrometer 9 corresponding to the corresponding time period according to the read screening voltage and its residence time, unifies the time reference of the whole system to match the mobility data, repeats the voltage scanning program of the planar differential mobility analyzer 2 according to the above preset initial voltage, termination voltage, and voltage step, and statistically averages the obtained multiple groups of mass spectrometer 9 data until the chemical ionization-differential mobility screening-mass spectrometry combined system stops running.

[0042] In a specific working mode with the reverse electrode configuration of the planar differential mobility analyzer 2 in the present invention, a standard aerosol sample is used for specific mobility screening in the fixed voltage mode, and is transmitted to the aerosol electrometer 6 and the mass spectrometer 9 through the special ion transfer interface 5 to obtain the ion transfer efficiency of the sample. The measurement results are as Figure 3 shown. The upper electrode plate 32 of the planar differential mobility analyzer 2 is grounded, the lower electrode plate 33 is connected to high-voltage negative electricity, the working voltage of the sheath gas circulation system 3 is set to 3.0 V, the pumping speed of the second vacuum pump 8 is set to 3 L / min, and the standard aerosol sample ions pass through the planar differential mobility analyzer 2 and are transmitted to the aerosol electrometer 6 and the mass spectrometer 9 through the special ion transfer interface 5, and its ion transfer efficiency can reach more than 50% at most.

[0043] In summary, the present invention uses a chemical ionization-differential mobility spectrometry-mass spectrometry combined system. The atmospheric pressure chemical ionization source can prevent the loss of smaller molecular clusters and avoid the extraction of organic substances in particulate matter by reagent ions. The planar differential mobility analyzer has high transmission efficiency and screening resolution. The combination of the two can directly perform in-situ ionization and efficient screening on environmental samples, and connect with a mass spectrometer to achieve online in-situ synchronous measurement of the chemical composition and mobility of gases / molecular clusters in the real atmospheric environment.

[0044] For those skilled in the art, it should be recognized that other different forms of changes or modifications can be made on the basis of the above description without departing from the core idea and basic concept contained in the present disclosure. Therefore, in any aspect, the embodiments should be regarded as exemplary with guiding significance, rather than strict limitations on the implementation modes. Any modifications, equivalent replacements, optimization improvements, etc. made to the implementation modes are within the protection scope of the present invention.

Claims

1. A chemical ionization-differential mobility spectrometry-mass spectrometry coupling system, characterized in that, Comprising: An atmospheric pressure chemical ionization source system (1), a planar differential mobility analyzer (2), a sheath gas circulation system (3) for providing sheath gas to the planar differential mobility analyzer (2), an ion transfer interface (5), an aerosol electrometer (6), and a mass spectrometer (9); The atmospheric pressure chemical ionization source system (1) includes a chemical ionization source main system (10), an ionization source (11), a power supply box (12), and a gas source (13); an air inlet (24) is provided at the side end of the chemical ionization source main system (10), and the air inlet (24) is connected to the gas source (13) through an air inlet pipe. The gas source (13) is used to provide sheath gas and reagent vapor; an air outlet (31) is also provided at the side end of the chemical ionization source main system (10), and the air outlet (31) is sequentially connected to a reagent dissolver (17), a particulate filter (18), and a first suction pump (20) through an air outlet pipe; a first sample outlet is provided at the rear end of the chemical ionization source main system (10), and the first sample outlet is connected to the planar differential mobility analyzer (2); a first sample inlet (23) is provided at the front end of the chemical ionization source main system (10), and the first sample inlet (23) is used to input a sample; The planar differential mobility analyzer (2) is connected to the front interface of the ion transfer interface (5) through a second sample outlet; the ion transfer interface (5) also has a rear interface and a side interface, which are respectively used to connect the mass spectrometer (9) and the aerosol electrometer (6); A flow limiting valve (7) and a second suction pump (8) are sequentially provided at the air outlet of the aerosol electrometer (6). The second suction pump (8) is used to suck the sample from the first sample outlet of the chemical ionization source main system (10) into the planar differential mobility analyzer (2) and then into the aerosol electrometer (6).

2. The chemical ionization-differential mobility spectrometry-mass spectrometry combined system according to claim 1, wherein The gas source (13) is respectively connected to the air inlet at the side end of the chemical ionization source main system (10) through a first air inlet pipe and a second air inlet pipe; a first flow controller (14) is provided on the first air inlet pipe to adjust the sheath gas flow; a second flow controller (16) and a reagent storage (15) are provided on the second air inlet pipe. The reagent storage (15) is used to store chemical reagents. The chemical reagents are blown off by the carrier gas provided by the gas source (13) to generate reagent vapor. The second flow controller (16) is used to adjust the reagent vapor flow; a third flow controller (19) is provided between the particulate filter (18) and the first suction pump (20) to adjust the tail gas flow.

3. The chemical ionization-differential mobility spectrometry-mass spectrometry combined system according to claim 1, wherein The chemical ionization source main system (10) includes an ion reaction chamber (28), a fixing module (26), and a transmission lens (27); The fixing module (26) is nested outside the ion reaction chamber (28) and is used to fix the ionization source (11); The transmission lens (27) is embedded on the surface of the fixing module (26) and is used to make the ionization source (11) project through the lens into the ion reaction chamber (28) to convert the reagent vapor into reagent ions and fully collide and react with the sample to be measured to generate sample ions to be measured; The ion reaction chamber (28) is a conical cylindrical body, and its radial body size adopts a variable diameter design for specifically matching the second sampling port of the planar differential mobility analyzer (2). A repulsion electrode (29) and an acceleration electrode (30) are provided inside the reaction chamber, and are respectively connected to the chemical ionization source voltage controller (21) through a high-voltage power line (22) for controlling the voltage to generate electric fields of different magnitudes.

4. The chemical ionization-differential mobility spectrometry-mass spectrometry combined system according to claim 1, wherein The chemical ionization source main system (10) further includes an insect-proof net (25).

5. The chemical ionization-differential mobility spectrometry-mass spectrometry combined system according to claim 1, wherein The planar differential mobility analyzer (2) adopts a special working mode of reverse electrode configuration, in which the upper electrode plate (32) is grounded and the lower electrode plate (33) is connected to a high-voltage power line for generating an electric field between the two electrode plates.

6. The chemical ionization-differential mobility spectrometry-mass spectrometry coupling system according to claim 1, characterized in that, The main body of the ion transmission interface (5) is specially connected by an insulating backing plate (34) and a support housing (35). The other side of the insulating backing plate (34) is closely attached to the lower electrode plate (33) of the planar differential mobility analyzer (2). Product ion through holes are provided in the middle of both the support housing (35) and the insulating backing plate (34). A straight first electrostatic dissipation material tube (36) is filled inside the through holes and is connected to the mass spectrometer (9) to form a sealed charged sample transmission channel. A second electrostatic dissipation material tube (37) is provided at the side interface of the ion transmission interface (5) and is connected to the air inlet of the aerosol electrometer (6) for transmitting charged sample ions.

7. The chemical ionization-differential mobility spectrometry-mass spectrometry combined system according to claim 1, characterized in that The system includes a control system (4). The control system (4) is respectively connected to the atmospheric pressure chemical ionization source system (1), the planar differential mobility analyzer (2), the sheath gas circulation system (3), the aerosol electrometer (6) and the mass spectrometer (9) through data lines for controlling the internal voltage and flow rate of the atmospheric pressure chemical ionization source system (1), the switch and positive / negative high-voltage change of the planar differential mobility analyzer (2), and the flow rate of the sheath gas circulation system (3), and collecting data information of the planar differential mobility analyzer (2), the aerosol electrometer (6) and the mass spectrometer (9) to monitor the operation status of the system in real time and store and read the corresponding data.

8. A working method of the system according to claim 7, characterized in that, Including: The gas source (13) continuously provides dry and clean gas. The control system (4) adjusts the flow rates of the inlet (24), outlet (31) of the chemical ionization source main system (10) and the sampling flow rate of the first sampling port (23) by controlling three flow controllers. At the same time, the chemical ionization source voltage controller (21) applies different voltages to the repulsion electrode (29) and the acceleration electrode (30) through the high-voltage power line (22) to obtain an electric field. The control system (4) displays the ionization source flow rate and the actual parameters of the electrodes in real time. The control system (4) controls the voltage of the lower electrode plate (33) of the planar differential mobility analyzer (2) and the flow rate of the sheath gas circulation system (3), and reads and stores in real time the screening voltage of the planar differential mobility analyzer (2), the voltage of the aerosol electrometer (6), the signal of the mass spectrometer (9) and the acquisition time corresponding to each data. The control system (4) is set with two modes: fixed voltage mode and scanning voltage mode. In the fixed voltage mode, the voltage of the lower electrode plate (33) is controlled to be a constant value, and the planar differential mobility analyzer (2) screens the target samples with corresponding mobilities at this voltage. In the scanning voltage mode, the initial voltage, termination voltage, and voltage step are respectively set for the lower electrode plate (33), and the planar differential mobility analyzer (2) sequentially scans within the set voltage range according to the established voltage step for mobility screening. In the fixed voltage mode, the control system (4) synchronously reads the data of the mass spectrometer (9), statistically averages the mass spectrometry data according to the preset time resolution until the system stops running. In the scanning voltage mode, the control system (4) extracts the data of the mass spectrometer (9) for the corresponding period according to the read screening voltage and its residence time, unifies the time reference of the system to match the mobility data, repeatedly executes the voltage scanning program of the planar differential mobility analyzer (2), and statistically averages the obtained mass spectrometry data until the system stops running.

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