Chemical ionization-differential mobility screening-mass spectrometry system and working method

Abstract

The present invention discloses a kind of chemical ionization-differential mobility screening-mass spectrometry system and working method, belong to the field of molecular cluster measurement technology, the present invention includes: atmospheric pressure chemical ionization source system, planar differential mobility analyzer, sheath gas circulation system, ion transmission interface, aerosol electrometer, mass spectrometer and control system; Chemical ionization source system and planar differential mobility analyzer are connected, planar differential mobility analyzer and its sheath gas circulation system form a circulating gas path, and planar differential mobility analyzer transmits the sample ions to be tested to aerosol electrometer and mass spectrometer detection by a special ion transmission interface; Control system connects atmospheric pressure chemical ionization source system, planar differential mobility analyzer and its sheath gas circulation system and mass spectrometer, provides high voltage and data collection, storage and reading. The present invention can realize the chemical composition of gas / molecular clusters in gas phase and efficient online in-situ synchronous monitoring of mobility.

Description

Technical Field

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

[0002] Chemical ionization (CI) is a soft ionization technique that ionizes samples through the reaction between reagent ions and sample molecules and is widely used in mass spectrometry. Chemical ionization atmospheric pressure interface time-of-flight mass spectrometry (CI-APi-ToF) has been applied to the real-time, online measurement of the chemical composition of various trace gases, molecular clusters, and aerosol particles in the ambient atmosphere using chemical ionization. A differential mobility analyzer (DMA) can measure true mobility and convert it to particle size. Coupled with an ionization source, the front end can ionize aerosols and efficiently separate target charged particles. Furthermore, combined with a mass spectrometer (DMA-MS), it can simultaneously measure aerosol structure and chemical composition. However, existing DMA-MS are only suitable for detecting clusters generated by electrospray or electrospray secondary ionization. There is a lack of in situ ionization techniques for gas-phase molecules and clusters that can be coupled to DMA-MS. Therefore, the development of ionization sources that can be coupled to DMA and tandem with a mass spectrometer for online, in situ measurements of environmental samples is of great significance.

[0003] Atmospheric pressure chemical ionization (APCI) sources coupled to mass spectrometers based on various chemical reagents have been widely used to monitor molecules in gas and nanoaerosol samples. Using an APCCI source coupled to a planar DMA tandem mass spectrometer allows for direct, online, in-situ monitoring of the structure and chemical composition of gaseous samples without any front-end processing, accurately identifying the growth of gaseous precursors into molecular clusters and even aerosols.

[0004] Among the published invention patents, the patent with authorization announcement number CN105632870A relates to an atmospheric pressure chemical ionization source for mass spectrometry. The atmospheric pressure chemical ionization source designed in this patent can provide pure product ions. The coupled mass spectrometer can realize online detection of the chemical composition and concentration of the sample to be tested, but it cannot simultaneously obtain the structural characteristic information of the sample. The patent with authorization announcement number CN113484402A relates to a planar differential mobility analyzer-mass spectrometer system based on an electrospray ionization source. The ion source used in this patent uses a liquid reagent to ionize the sample. Dissolution or extraction effects are prone to occur during the ionization of gas molecules and clusters. In addition, the charging efficiency of this device is low, making it unsuitable for in situ measurement of atmospheric environment samples. Summary of the Invention

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

[0006] To achieve the above-mentioned object, the specific technical solution adopted by the present invention is as follows: a chemical ionization-differential mobility screening-mass spectrometry system, comprising: an atmospheric pressure chemical ionization source system, a planar differential mobility analyzer, a sheath gas circulation system for providing sheath gas to the planar differential mobility analyzer, an ion transmission 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 connected to the reagent dissolver, the particulate filter, and the first air pump in sequence through the air outlet pipe for discharging exhaust 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 transmission interface through the second sample outlet; the ion transmission interface is also provided with a rear interface and a side interface, which are respectively used to connect to the mass spectrometer and the aerosol electrometer;

[0009] The aerosol electrometer gas outlet is sequentially provided with a flow limiting valve and a second gas pump, and the second gas pump is used to draw 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] Furthermore, the gas source is connected to the gas inlet at the side end of the chemical ionization source main system through a first gas inlet pipe and a second gas inlet pipe respectively; the first gas inlet pipe is provided with a first flow controller for adjusting the sheath gas flow; the second gas inlet pipe is provided with a second flow controller and a reagent reservoir, the reagent reservoir 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; a third flow controller is provided between the particulate filter and the first vacuum pump for adjusting the exhaust gas flow.

[0011] Furthermore, 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 and is used to fix the ionization source;

[0013] The transmission lens is embedded in the surface of the fixed module, and is used to project the ionization source through the lens to the ion reaction chamber to convert the reagent vapor into reagent ions, which fully collide and react with the sample to be tested to produce the sample ions to be tested;

[0014] The ion reaction chamber is a tapered cylindrical barrel with a variable radial diameter designed to specifically match the second sample inlet of the planar differential mobility analyzer. A repeller electrode and an accelerating electrode are provided inside the reaction chamber, which are respectively connected to the chemical ionization source voltage controller via high-voltage power lines. The electrodes are used to control the voltage to generate electric fields of different magnitudes so that the sample ions are guided to the first sample outlet at a speed parallel to the direction of the electric field.

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

[0016] Furthermore, the planar differential mobility analyzer adopts a special working mode of reverse electrode configuration, wherein the upper electrode plate is grounded and the lower electrode plate is connected to a high-voltage power line, so as to generate an electric field between the two electrode plates; sample ions enter the second inlet 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, sample ions with specific electric mobility flow out from the second outlet, thereby realizing screening of the sample ions.

[0017] Furthermore, the ion transmission interface body is composed of a specially connected insulating pad and a supporting shell, and the other side of the insulating pad is tightly fitted with the lower electrode plate of the planar differential mobility analyzer; the support shell and the insulating pad are both provided with product ion through holes in the middle, and the through hole is filled with a straight first electrostatic dissipative material tube, so that no static electricity accumulation is generated inside the through hole while forming an insulating space between the lower electrode plate and the mass spectrometer, and it is connected to the mass spectrometer to form a closed charged sample transmission channel; the side interface of the ion transmission interface is provided with a second electrostatic dissipative material tube, which is connected to the air inlet of the aerosol electrometer for transmitting charged sample ions.

[0018] Furthermore, the system includes a control system, which is 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 internal voltage and flow of the atmospheric pressure chemical ionization source system, the switch and positive / negative high voltage changes of the planar differential mobility analyzer, and the flow rate of the sheath gas circulation system, and collect data information from the planar differential mobility analyzer, the aerosol electrometer and the mass spectrometer, monitor the operating status of the system in real time, and store and read corresponding data.

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

[0020] The gas source continuously provides sufficient, dry and clean gas; the control system adjusts the inlet and outlet flow rates of the chemical ionization source main system and the injection flow rate of the first injection port by controlling three-way flow controllers; at the same time, the chemical ionization source voltage controller applies different voltages to the repeller electrode and the accelerating electrode through the high-voltage power line to obtain an electric field; the control system displays the actual parameters of the ionization source flow and the electrode 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 the screening voltage of the planar differential mobility analyzer, the voltage of the aerosol electrometer, the signal of the mass spectrometer and the corresponding acquisition time of each data in real time.

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

[0023] In the fixed voltage mode, the control system synchronously reads the mass spectrometer data and statistically averages the mass spectrometer 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 of the corresponding time period based on the read screening voltage and its residence time, and unifies the time base of the entire system to match the mobility data, repeatedly executes the voltage scanning program of the planar differential mobility analyzer, and statistically averages the obtained mass spectrometer data until the chemical ionization-differential mobility screening-mass spectrometry system stops running.

[0024] The beneficial effects of the present invention compared with the prior art are as follows: a chemical ionization-differential mobility screening-mass spectrometry system is adopted, the atmospheric pressure chemical ionization source can prevent the loss of smaller molecular clusters and avoid the extraction of organic matter 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 efficient screening of environmental samples, and connect with a mass spectrometer to realize online in-situ synchronous measurement of the chemical composition and mobility of gas / molecular clusters in a real atmospheric environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

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

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

[0028] Figure 3 This is a graph of the ion transmission efficiency of the sample when it is in the specific reverse connection mode of the planar differential mobility analyzer combined with a special ion transmission interface;

[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 transmission interface 5, the aerosol electrometer 6, the current 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 reservoir 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 repeller electrode 29, the accelerating electrode 30, the air outlet 31, the upper electrode plate 32, the lower electrode plate 33, the insulating pad 34, the support shell 35, the first static dissipative material tube 36, and the second static dissipative material tube 37. DETAILED DESCRIPTION

[0030] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent like or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present invention, as detailed in the appended claims.

[0031] The terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The singular forms "a," "the," and "the" used in this invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as 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 merely used to distinguish information of the same type from one another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present invention. Depending on the context, the term "if" as used herein may be interpreted as "when," "when," or "in response to determining."

[0033] The present invention will be described in detail below with reference to the accompanying drawings. Unless there is any conflict, the features of the following embodiments and implementations may be combined with each other.

[0034] An embodiment of the present invention provides a chemical ionization-differential mobility screening-mass spectrometry system and working method, which uses a chemical ionization source to efficiently ionize environmental samples, couples with a planar differential mobility analyzer to achieve high-resolution screening of the mobility of charged products, and connects with a mass spectrometer to synchronously measure the chemical composition and particle size structure of charged targets.

[0035] like Figure 1 As shown in FIG, the main configuration of the present invention includes 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 transmission interface 5, an aerosol electrometer 6, and a mass spectrometer 9. The internal sample route diagram of the main parts of the system of the present invention, the atmospheric pressure chemical ionization source system 1, the planar differential mobility analyzer 2, and the mass spectrometer 9 is shown in FIG. Figure 2 shown.

[0036] The atmospheric pressure chemical ionization source system 1 is connected to the planar differential mobility analyzer 2, and the sheath gas circulation system 3 provides a clean sheath gas circulation gas path for the planar differential mobility analyzer 2; the planar differential mobility analyzer 2 is connected to the ion transmission interface 5, and the ion transmission interface 5 is also provided with a reverse interface and a side interface, which are respectively used to connect to the mass spectrometer 9 and the aerosol electrometer 6, and the outlet of the aerosol electrometer 6 is connected to the current limiting valve 7 and the second air pump 8 in sequence; 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 of the atmospheric pressure chemical ionization source system 1, the switch and positive / negative high voltage changes of the planar differential mobility analyzer 2, and the flow rate of the sheath gas circulation system 3, 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 comprises: 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 storage 15, a reagent dissolver 17, a particle filter 18 and a first air pump 20; the chemical ionization source main system 10 is provided with an air inlet 24 and an air outlet 31 at the side end, a first sample inlet 23 at the front end and a first sample outlet at the rear end; the gas source 13 is provided to the system through the first air inlet pipe and the second air inlet pipe Gas supply, the first air inlet pipe is controlled by the first flow controller 14 to provide clean sheath gas, and the second air inlet pipe is controlled by the second flow controller 16 to provide carrier gas, which blows out the chemical reagent in the reagent reservoir 15 to generate reagent vapor. The first air inlet pipe and the second air inlet pipe enter the chemical ionization source main system 10 through the three-way pipe joint together from the air inlet 24, and the exhaust gas is filtered through the reagent dissolver 17 and the particulate filter 18 through the air outlet 31 and then sucked out by the first air pump 20. The total flow is controlled by the third flow controller 19.

[0038] The chemical ionization source main system 10 also includes an insect screen 25, a fixing module 26, a transmissive lens 27, and an ion reaction chamber 28. The ion reaction chamber 28 utilizes a specially designed cylindrical structure with gradually decreasing radial dimensions to accommodate the planar differential mobility analyzer 2. Simultaneously, the system and its air intake configuration are optimized based on the varying dimensions of the cylindrical body to ensure that the sample and sheath gases maintain a balanced airflow, forming a stable laminar flow. Furthermore, by adding a repeller electrode 29 and an accelerating electrode 30 to the system, the tapered interior of the reaction chamber, with its variable diameter design, further facilitates the focusing and movement of sample ions. The sample to be tested enters through the first inlet 23 and moves toward the ion reaction chamber 28. The fixing module 26 is nested outside the ion reaction chamber 28 to secure the ion source 11. The transmissive lens 27 is embedded in the surface of the fixing module 26, allowing the ion source 11 to project through the lens into the ion reaction chamber 28, converting the reagent vapor into reagent ions, which then collide and react with the sample to produce sample ions. The power supply box 12 continuously supplies power to the ion source 11 to ensure continuous operation. The chemical ionization source voltage controller 21 applies different voltages to the repeller electrode 29 and the accelerating electrode 30 through the high-voltage power line 22 to generate an electric field, so that the sample ions are focused and obtain a speed 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 flow of sheath gas and reagent vapor, they move smoothly along the preset motion trajectory toward the first sample outlet, ensuring that the sample ions are accurately and efficiently introduced into the planar differential mobility analyzer 2 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 by the suction force of the second vacuum pump 8. At the same time, the planar differential mobility analyzer 2 adopts a special working mode of reverse electrode configuration, wherein the upper electrode plate 32 is grounded and the lower electrode plate 33 is connected to the high-voltage power line to ensure that the sample ions ionized by the chemical ionization source main system 10 are effectively transmitted to the second sample inlet of the planar differential mobility analyzer 2. The control system 4 controls the voltage switch 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 is controlled by the control system 4 at a flow rate and enters the planar differential mobility analyzer 2 from the upper end and flows out from the lower end; the sample ions enter from the pores of the upper electrode plate 32 and are affected by the combined action of the sheath gas laminar flow and the electric field. The sample ions of a specific particle size flow out from the pores of the lower electrode plate 33 to achieve sample screening and then pass to the ion transmission interface 5.

[0040] The main body of the ion transmission interface 5 is composed of a special connection between an insulating pad 34 and a supporting shell 35, which is specially adapted to the connection between the planar differential mobility analyzer 2 and the mass spectrometer 9 in a specific reverse electrode working mode; the other side of the insulating pad 34 is tightly fitted with the lower electrode plate 33 of the planar differential mobility analyzer 2; the middle of the supporting shell 35 and the insulating pad 34 are both provided with product ion through holes, and a straight first electrostatic dissipative material tube 36 is used to fill the interior to ensure that ions fly smoothly along the pipeline to prevent ion loss, so that no static electricity accumulation is generated inside the through hole under the premise of forming an insulating space between the lower electrode plate 33 and the mass spectrometer 9, and the first electrostatic dissipative material tube 36 and the mass spectrometer 9 are connected. The connection can form a closed charged sample transmission channel with high transmission efficiency; another interface is provided on the side of the ion transmission interface 5, and a straight second electrostatic dissipative material tube 37 is used to connect to the air inlet of the aerosol electrometer 6. The suction force of the second vacuum pump 8 draws part of the charged sample ions into the aerosol electrometer 6; the sample ions after screening 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 transmission interface 5. The control system 4 reads and collects 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 in real time.

[0041] The gas source 13 continuously provides sufficient, dry, and clean gas. The control system 4 regulates the flow rates at the chemical ionization source main system 10's gas inlet 24 and gas outlet 31, as well as the sample flow rate at the first sample inlet 23, by controlling three flow controllers. Simultaneously, the chemical ionization source voltage controller 21 applies varying voltages to the repeller electrode 29 and the accelerating electrode 30 via the high-voltage power line 22 to generate an electric field. The control system 4 displays the ionization source flow rate and actual electrode parameters 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. It also reads and stores the planar differential mobility analyzer 2's screening voltage, the voltage of the aerosol electrometer 6, the signal from the mass spectrometer 9, and the corresponding acquisition time for each data point in real time. The control system 4 can be set to two modes: fixed voltage and scanning voltage: 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 sample corresponding to the mobility under the specific voltage; in the scanning voltage mode, the initial voltage, the end 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 to perform mobility screening. In the fixed voltage mode, the control system 4 synchronously reads the mass spectrometer 9 data, and statistically averages the mass spectrometer data according to the preset time resolution until the system stops running; in the scanning voltage mode, the control system 4 extracts the mass spectrometer 9 data of the corresponding period according to the read screening voltage and its residence time, unifies the time base of the entire system to match the mobility data, and repeatedly executes the voltage scanning program of the planar differential mobility analyzer 2 according to the above-mentioned preset initial voltage, end voltage and voltage step, and statistically averages the multiple groups of mass spectrometer 9 data obtained until the chemical ionization-differential mobility screening-mass spectrometry system stops running.

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

[0043] In summary, the present invention adopts a chemical ionization-differential mobility screening-mass spectrometry system. The atmospheric pressure chemical ionization source can prevent the loss of smaller molecular clusters and avoid the extraction of organic matter 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 of environmental samples, and connect with the mass spectrometer to realize online in situ synchronous measurement of the chemical composition and mobility of gas / molecular clusters in a real atmospheric environment.

[0044] Those skilled in the art will recognize that other variations or modifications may be made based on the above description without departing from the core ideas and basic concepts of the present disclosure. Therefore, the embodiments should be considered as examples with guiding significance in all respects, rather than strict limitations on the implementation methods. Any modifications, equivalent substitutions, optimizations, and improvements to the implementation methods are within the scope of protection of the present invention.

Claims

1. A chemical ionization-differential mobility screening-mass spectrometry system, characterized in that: include: A normal 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 transmission interface (5), an aerosol electrometer (6), and a mass spectrometer (9); The atmospheric pressure chemical ionization source system (1) comprises a chemical ionization source main system (10), an ionization source (11), a power supply box (12), and a gas source (13); a side end of the chemical ionization source main system (10) is provided with an air inlet (24), the air inlet (24) is connected to the gas source (13) through an air inlet pipe, and the gas source (13) is used to provide sheath gas and reagent vapor; a side end of the chemical ionization source main system (10) is also provided with an air outlet (31), the air outlet (31) is connected to a reagent dissolver (17), a particle filter (18), and a first air pump (20) in sequence through an air outlet pipe; a rear end of the chemical ionization source main system (10) is provided with a first sample outlet, the first sample outlet is connected to the planar differential mobility analyzer (2); a front end of the chemical ionization source main system (10) is provided with a first sample inlet (23), 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 transmission interface (5) via the second sample outlet; the ion transmission interface (5) is also provided with a rear interface and a side interface, which are respectively used to connect to the mass spectrometer (9) and the aerosol electrometer (6); The air outlet of the aerosol electrometer (6) is provided with a flow limiting valve (7) and a second air pump (8) in sequence. The second air pump (8) is used to draw 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 screening-mass spectrometry system according to claim 1, characterized in that: The gas source (13) is connected to the gas inlet at the side end of the chemical ionization source main system (10) through a first gas inlet pipe and a second gas inlet pipe respectively; the first gas inlet pipe is provided with a first flow controller (14) for adjusting the sheath gas flow; the second gas inlet pipe is provided with a second flow controller (16) and a reagent storage (15), 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, and 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 vacuum pump (20) for adjusting the exhaust gas flow.

3. The chemical ionization-differential mobility screening-mass spectrometry system according to claim 1, characterized in that: 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 in the surface of the fixed module (26) and is used to project the ionization source (11) through the lens to the ion reaction chamber (28) to convert the reagent vapor into reagent ions, and fully collide with the sample to be tested to produce the sample ions to be tested; The ion reaction chamber (28) is a tapered cylindrical barrel, and its radial barrel size adopts a variable diameter design to specifically match the second injection port of the planar differential mobility analyzer (2). A repeller electrode (29) and an accelerating electrode (30) are provided inside the reaction chamber, which 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 sizes.

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

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

6. The chemical ionization-differential mobility screening-mass spectrometry system according to claim 1, characterized in that: The main body of the ion transmission interface (5) is composed of an insulating pad (34) and a supporting shell (35) that are specially connected. The other side of the insulating pad (34) is tightly fitted with the lower electrode plate (33) of the planar differential mobility analyzer (2); the middle parts of the supporting shell (35) and the insulating pad (34) are both provided with product ion through holes, and the interior of the through holes is filled with a straight first electrostatic dissipative material tube (36), which is connected to the mass spectrometer (9) to form a closed charged sample transmission channel; the side interface of the ion transmission interface (5) is provided with a second electrostatic dissipative material tube (37), which is connected to the air inlet of the aerosol electrometer (6) and is used to transmit charged sample ions.

7. The chemical ionization-differential mobility screening-mass spectrometry system according to claim 1, characterized in that: The system comprises a control system (4), which is respectively connected to a normal-pressure chemical ionization source system (1), a planar differential mobility analyzer (2), a sheath gas circulation system (3), an aerosol electrometer (6), and a mass spectrometer (9) via data lines, and is used to control the internal voltage and flow of the normal-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 collect data information from the planar differential mobility analyzer (2), the aerosol electrometer (6), and the mass spectrometer (9) to monitor the operating status of the system in real time, and to store and read corresponding data.

8. A working method based on the system according to claim 7, characterized in that: include: The gas source (13) continuously provides dry and clean gas; The control system (4) adjusts the flow rates of the air inlet (24), the air outlet (31) and the injection flow rate of the first injection port (23) of the chemical ionization source main system (10) by controlling the three-way flow controller; at the same time, the chemical ionization source voltage controller (21) applies different voltages to the repeller electrode (29) and the accelerating electrode (30) through the high-voltage power line (22) to obtain an electric field; the control system (4) displays the actual parameters of the ionization source flow rate and 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 configured to have two modes: a fixed voltage mode and a 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 target samples with corresponding mobility under the voltage. In the scanning voltage mode, the initial voltage, the end voltage, and the voltage step length are respectively set for the lower electrode plate (33), and the planar differential mobility analyzer (2) scans sequentially within the set voltage range according to the established voltage step length to perform mobility screening. In the fixed voltage mode, the control system (4) synchronously reads the data of the mass spectrometer (9), and statistically averages the mass spectrometer data according to the preset time resolution until the system stops running; in the scanning voltage mode, the control system (4) extracts the mass spectrometer (9) data of the corresponding time period according to the read screening voltage and its residence time, and unifies the system's time base to match the mobility data, repeatedly executes the voltage scanning program of the planar differential mobility analyzer (2), and statistically averages the obtained mass spectrometer data until the system stops running.

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