Rapid recovery ion mobility spectrometry device and rapid recovery method

Abstract

The fast recovery ion mobility spectrometry device comprises a migration tube, a diffusion permeable membrane, an ionization source, an ion gate and a Faraday disc are sequentially arranged in the migration tube from one end to the other end at intervals, the migration tube is provided with a pre-amplifier, a purging cavity is defined between the diffusion permeable membrane and the ionization source, and the Faraday disc is arranged in the purging cavity. A sample injection cavity is defined at one end, deviating from the ionization source, of the diffusion and permeation membrane, an ionization cavity is defined between the ionization source and the ion gate, a migration cavity is defined between the ion gate and the Faraday disc, and the migration pipe is connected with a gas supply pipe which is used for conveying clean gas to the sample injection cavity and the purging cavity. Gas purifying and conveying systems at the two ends of the diffusion and permeation membrane are purged; the fast-recovery ion mobility spectrometry device comprises the migration tube, the structural design is reasonable, redundant measured substances on the two sides of the diffusion and permeation membrane can be rapidly cleaned at the same time, and therefore the ion mobility spectrometry device is helped to rapidly recover the usable state.

Description

Technical Field

[0001] This invention relates to the field of ion migration technology, and in particular to a device and method for rapidly recovering ion migration spectra. Background Technology

[0002] Ion mobility spectrometry (IMS) is a material analysis technique based on the migration behavior of gaseous ions in an electric field. Its core principle is to ionize the analyte to form charged ions, and then separate and detect these ions by utilizing the difference in their migration rates during collisions with neutral gas molecules in an electric field. The process consists of three steps: First, sample molecules are ionized by an ionization source (such as corona discharge, radioactive sources, or laser ionization). Then, different ions simultaneously enter a migration tube, where they are driven towards the detector by a uniform electric field. Due to differences in mass, charge, shape, and collision cross-section, different ions migrate through the migration tube at specific rates, resulting in temporal separation. Finally, the detector generates a "migration spectrum" based on the ion arrival time. Qualitative analysis is achieved through characteristic migration times, while signal intensity is used for quantitative analysis. As a trace detection tool, IMS offers sensitivity down to the ppb (parts per billion) level, with advantages such as fast response, small size, and no need for complex pretreatment. It is widely used in security inspection (explosives / drug detection), environmental pollutant monitoring, and biomedical diagnostics. However, its high performance is highly dependent on the cleanliness and stability of the system. Generally, to maintain the stability and cleanliness of the ion migration area, a diffusion-permeable membrane with permeability is used to isolate the external environment from the internal ion migration environment, which includes an ionization zone and a migration zone. However, when detecting high-concentration samples, the membrane easily adsorbs excessive amounts of the analyte, requiring a long desorption time. The desorption process is non-selective and occurs on both sides of the membrane. Without special design, excess substances can also enter the ion migration side, causing the substance to remain in the migration zone for a long time and continuously ionize, consuming the ions generated by the ion source and thus preventing the detection of other substances.

[0003] In traditional IMS systems containing diffusion-permeable membranes, a large amount of analyte accumulates within the membrane as the concentration of the analyte increases. Even if the external gas concentration decreases or reaches zero, the accumulated analyte within the membrane requires time to release. Due to the presence of a purification gas flow within the ion mobility spectrometer, the concentration remains consistently low. Consequently, the analyte within the diffusion-permeable membrane tends to be released uniformly to both sides, rather than solely towards the injection chamber, thus reducing the recovery rate. Furthermore, once the analyte enters the ionization region and is ionized, it needs to migrate to the migration region to generate a signal, ultimately being adsorbed by the gas purification material. The diffusion of the gas further prolongs the entire recovery process.

[0004] Therefore, there is a need to develop a fast-recovery ion mobility spectrometry (IMS) device that can simultaneously and quickly clean excess analytes on both sides of the IMS film, thereby helping the IMS device to clean up quickly. For monitoring-type IMS, this can improve the real-time performance of the monitored concentration, and for detection-type devices, it can restore the device to a detectable state more quickly. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a rapidly recoverable ion mobility spectrometer, which effectively overcomes the defects of the prior art.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A rapid recovery ion mobility spectrometry device includes a migration tube. A diffusion-permeable membrane, an ionization source, an ion gate, and a Faraday disk are sequentially arranged from one end to the other within the migration tube. The migration tube is equipped with a preamplifier. A purge chamber is defined between the diffusion-permeable membrane and the ionization source. A sample inlet chamber is defined at the end of the diffusion-permeable membrane opposite to the ionization source. An ionization chamber is defined between the ionization source and the ion gate. A migration chamber is defined between the ion gate and the Faraday disk. The migration tube is connected to a gas purification and delivery system that supplies clean gas to the sample inlet chamber and the purge chamber, and purges both ends of the diffusion-permeable membrane.

[0007] Based on the above technical solution, the present invention can be further improved as follows.

[0008] Furthermore, the sample injection chamber wall is provided with a first gas port communicating with its interior, the purge chamber wall is provided with a second gas port communicating with its interior, and the migration chamber is provided with a third gas port at the end away from the ion gate. The gas purification and delivery system includes a first gas purification and delivery system and a second gas purification and delivery system. The first gas port is connected to the first gas purification system, and the second and third gas ports are respectively connected to the second gas purification system. The first gas purification system is used to output purified gas into the sample injection chamber and purge one end of the diffusion permeation membrane. The second gas purification system is used to deliver purified gas through the third gas port and discharge it from the second gas port, thereby purging the other end of the diffusion permeation membrane.

[0009] Furthermore, the aforementioned second gas purification system includes a second gas pump, a second gas purification device, and a second control valve. The ionization chamber has a fourth gas port on its wall. The inlet of the second gas pump is connected to the fourth gas port via a pipeline. The outlet of the second gas pump is connected to the inlet of the second gas purification device via a pipeline. The outlet of the second gas purification device is connected to the third gas port via a pipeline. The second gas port is connected to the valve port of the second control valve via a pipeline. The valve port of the second control valve is connected to the inlet of the second gas pump via a pipeline.

[0010] Furthermore, it also includes an air guiding component, which is installed in the purge chamber and its outer periphery is sealed to the inner wall of the migration tube. The air guiding component has an air hole at its center that extends through both ends.

[0011] Furthermore, the gas guiding component has a frustum-shaped gas guiding cavity at one end near the diffusion permeation membrane, and the center of the gas guiding cavity is connected to the gas hole.

[0012] Furthermore, the aforementioned air guiding components are made of metal, ceramic, or anti-adsorption plastic.

[0013] Furthermore, the aforementioned air guiding component is provided with a heating device for heating the air passing through the aforementioned air holes.

[0014] Furthermore, the aforementioned first gas purification system includes a first control valve, a first air pump, and a first gas purification device. The outlet of the first air pump is connected to the inlet of the first gas purification device via a pipeline, the outlet of the first gas purification device is connected to the valve port of the first control valve via a pipeline, and the valve port of the first control valve is connected to the first gas port via a pipeline.

[0015] Furthermore, it also includes a sampling pump. The first control valve is a two-position three-way valve. One valve port of the two-position three-way valve is connected to the outlet of the first gas purification device via a pipeline, and the other two valve ports of the two-position three-way valve are respectively connected to the first gas port and the inlet of the sampling pump via pipelines.

[0016] The beneficial effects of this invention are: the reasonable structural design can simultaneously and quickly clean the excess analyte on both sides of the diffusion permeation membrane, thereby helping the ion mobility spectrometry equipment to quickly return to a usable state.

[0017] This embodiment also provides a rapid recovery method for an ion mobility spectrometry device, comprising the following steps: Step 1: Turn on the sampling pump to take samples; Step 2: The ion mobility spectrometer synchronously monitors the concentration of the gas to be measured at the diffusion permeation membrane. If the concentration is lower than the set threshold, sampling continues. If the concentration is not lower than the set threshold, the alarm of the ion mobility spectrometer will continue to sound. After the alarm time period t1, it switches to the backflushing state and backflushes both sides of the diffusion permeation membrane simultaneously. After the backflushing continues for time period t2, it switches to the sampling state. Step 3: In the sampling state, if the concentration of the gas being measured does not exceed the set threshold within the time period t3, the alarm will stop; otherwise, switch to the backflushing state to continue purging until the concentration of the gas being measured does not exceed the set threshold within the time period t3 in the sampling state. Attached Figure Description

[0018] Figure 1 A simplified structural diagram of an existing IMS containing a diffusion permeation membrane; Figure 2 A schematic diagram of the structure of the rapid recovery ion mobility spectrometer of the present invention (backflush state); Figure 3 This is a diagram showing the operational status of the rapid recovery ion mobility spectrometry device of the present invention.

[0019] The attached diagram lists the components represented by each number as follows: 1. Migration tube; 2. Diffusion permeation membrane; 3. Ionization source; 4. Ion gate; 5. Faraday disk; 6. Preamplifier; 7. Gas guide component; 11. Purge chamber; 12. Sample injection chamber; 13. Ionization chamber; 14. Migration chamber; 81. First control valve; 82. First gas pump; 83. First gas purification device; 84. Sampling pump; 91. Second gas pump; 92. Second gas purification device; 93. Second control valve. Detailed Implementation

[0020] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0021] like Figure 1 As shown in the attached figure, this is a traditional IMS containing a diffusion-permeable membrane. a is the sample inlet chamber, b is the diffusion-permeable membrane, c is the ionization source (which can be a radioactive material or a discharge ionization device), d is the ionization chamber (including the region from the diffusion-permeable membrane to the ion gate e), e is the ion gate, f is the migration chamber (including the region from the ion gate to the Faraday disk), g is the Faraday disk used to collect the ion-forming current, h is the preamplifier used to convert the ion current into a detectable voltage signal, i is the gas pump used to extract the migrating gas, j is the sampling pump used to draw external gas into the sample inlet chamber so that the analyte gas permeates into the ionization region under the concentration gradient, and k is the gas purifier used to adsorb the permeated water vapor and analyte gas. The dashed arrows in the figure indicate the direction of ion movement, and the solid arrows indicate the direction of gas flow.

[0022] In traditional ion mobility spectrometry (IMP) equipment, a gas pump drives the gas flow into the sample injection chamber. Due to the barrier of the diffusion-permeable membrane, most of the gas cannot enter the IMP equipment, thus ensuring stable operation. When the concentration of the analyte increases, a large amount of the analyte accumulates inside the diffusion-permeable membrane. Even if the external gas concentration decreases or reaches zero, the analyte accumulated inside the diffusion-permeable membrane requires time to release. Because there is a purification gas flow inside the IMP equipment, the concentration remains very low. The substance inside the diffusion-permeable membrane tends to be released evenly to both sides, rather than only into the sample injection chamber, thus reducing the recovery rate.

[0023] Example 1 like Figure 2 and 3( Figure 2 and Figure 3 As shown in the diagram (solid line + arrow indicates airflow direction, dashed line + arrow indicates ion movement direction), the rapid recovery ion mobility spectrometry device of this embodiment includes a migration tube 1. The migration tube 1 is provided with a diffusion permeation membrane 2, an ionization source 3, an ion gate 4, and a Faraday disk 5 arranged sequentially from one end to the other. The migration tube 1 is provided with a preamplifier 6. A purge chamber 11 is defined between the diffusion permeation membrane 2 and the ionization source 3. A sample inlet chamber 12 is defined at the end of the diffusion permeation membrane 2 away from the ionization source 3. An ionization chamber 13 is defined between the ionization source 3 and the ion gate 4. A migration chamber 14 is defined between the ion gate 4 and the Faraday disk 5. The migration tube 1 is connected to a gas purification and delivery system that delivers clean gas to the sample inlet chamber 12 and the purge chamber 11 respectively, and purges both ends of the diffusion permeation membrane 2.

[0024] In this embodiment, the rapid recovery ion mobility spectrometry (IMS) device can enter a backflushing state if the analyte is detected during backflushing. At this time, the gas purification and delivery system delivers clean gas into the cavities at both ends of the diffusion membrane 2. The purified gas is used to purge both ends (both sides) of the diffusion membrane 2, effectively helping to quickly desorb residual analytes from the diffusion membrane 2, thereby achieving cleaning of the diffusion membrane 2. The overall structural design is reasonable, allowing for simultaneous and rapid cleaning of excess analytes on both sides of the diffusion membrane, thus helping the ion mobility spectrometry device quickly return to a usable state.

[0025] In a preferred embodiment, the sample injection chamber 12 has a first air port communicating with its interior, the purge chamber 11 has a second air port communicating with its interior, and the migration chamber 14 has a third air port at the end away from the ion gate 4. The gas purification and delivery system includes a first gas purification and delivery system and a second gas purification and delivery system. The first air port is connected to the first gas purification system, and the second and third air ports are respectively connected to the second gas purification system. The first gas purification system is used to output purified gas into the sample injection chamber 12 and purge one end of the diffusion permeation membrane 2. The second gas purification system is used to deliver purified gas through the third air port and discharge it from the second air port, thereby purging the other end of the diffusion permeation membrane 2.

[0026] In the above implementation scheme, the gas purification and delivery system includes two systems. One system (the first gas purification system) mainly targets the sample inlet chamber 12 at one end of the diffusion permeation membrane 2, delivering clean gas to the sample inlet chamber 12 and purging one end of the diffusion permeation membrane 2. The other system (the second gas purification system) mainly targets the purge chamber 11 at the other end of the diffusion permeation membrane 2, delivering clean gas to the purge chamber 11 and purging the other end of the diffusion permeation membrane 2. The coordinated purging can cause a large amount of the analyte accumulated in the diffusion permeation membrane 2 to be rapidly released under the combined action of the clean gases at both ends, achieving an effective back-purge purification effect.

[0027] In a preferred embodiment, the system further includes an air guide component 7, which is installed in the purge chamber 11 and its outer periphery is sealed to the inner wall of the migration tube 1. The air guide component 7 has an air hole at its center that extends through both ends.

[0028] In the above implementation scheme, the first air port is located on the side wall of the cavity between the air guiding component 7 and the diffusion permeation membrane 2. Since the size of the air port is small, during purging, the probability of gas entering the ionization cavity 13 due to diffusion is minimized. In this state, the gas in the ionization cavity 13 is mostly clean gas, so the air state can be restored as soon as possible.

[0029] In this embodiment, the gas guiding member 7 has a frustoconical gas guiding cavity at one end near the diffusion permeation membrane 2, and the center of the gas guiding cavity is connected to the air hole. The shape design is reasonable, which facilitates the entry of clean gas and effectively purges one end of the diffusion permeation membrane 2.

[0030] In this embodiment, the gas guiding component 7 is a metal part, a ceramic part, or an anti-adsorption plastic part. More specifically, the gas guiding component 7 is made of metal (aluminum alloy, stainless steel, etc.), ceramic (alumina, aluminosilicate, etc.), or anti-adsorption plastic (fluorinated resin, PEEK, polyimide, etc.), wherein the pore size ranges from 0.1mm to 10mm.

[0031] In this embodiment, the gas guiding component 7 is provided with a heating device for heating the gas passing through the aforementioned pores. Heating by this device can further reduce gas adsorption and accelerate gas desorption.

[0032] In a preferred embodiment, the first gas purification system includes a first control valve 81, a first air pump 82, and a first gas purification device 83. The outlet of the first air pump 82 is connected to the inlet of the first gas purification device 83 via a pipeline, and the outlet of the first gas purification device 83 is connected to the valve port of the first control valve 81 via a pipeline. The valve port of the first control valve 81 is connected to the first gas port via a pipeline.

[0033] In the above implementation scheme, the first air pump 82 operates, and gas is drawn in from the external environment. After the first gas purification device 83 adsorbs the polluting gas that may exist in the environment, the clean airflow enters the purge chamber 11 through the first control valve 81 to clean the corresponding end (one side) of the diffusion permeation membrane 2. Since the incoming gas has been cleaned, it can help the residual test substance on the diffusion permeation membrane 2 to desorb quickly. Together with the second gas purification system, the other end (one side) of the diffusion permeation membrane 2 is cleaned, thus achieving effective cleaning of the diffusion permeation membrane 2.

[0034] As a preferred implementation method, such as Figure 1 As shown ( Figure 1 The middle arrow indicates the airflow direction. It also includes a sampling pump 84. The first control valve 81 is a two-position three-way valve. One valve port (valve port A) of the two-position three-way valve is connected to the outlet of the first gas purification device 83 through a pipeline. The other two valve ports (valve port B and valve port C) of the two-position three-way valve are respectively connected to the first gas port and the inlet of the sampling pump 84 through pipelines.

[0035] Example 2 In this solution, when backflushing cleaning is not required (i.e., when...) Figure 3 (As shown in the sampling state), the first control valve 81 switches to connect valve port B and valve port C, and the sampling pump 84 draws external gas into the sample inlet chamber 12 so that the gas to be measured can "pass through" the diffusion permeation membrane 2 and permeate into the ionization chamber 13 under the concentration gradient; when backflushing is required, the first control valve 81 switches back to connect valve port A and valve port B (as shown in the sampling state). Figure 2 (As shown in the backflush state), the control is very simple and quick.

[0036] As a preferred implementation method, such as Figure 2 and 3 As shown, the second gas purification system includes a second gas pump 91, a second gas purification device 92, and a second control valve 93. The ionization chamber 13 has a fourth gas port on its wall. The inlet of the second gas pump 91 is connected to the fourth gas port via a pipeline. The outlet of the second gas pump 91 is connected to the inlet of the second gas purification device 92 via a pipeline. The outlet of the second gas purification device 92 is connected to the third gas port via a pipeline. The second gas port is connected to the valve port of the second control valve 93 via a pipeline. The valve port of the second control valve 93 is connected to the inlet of the second gas pump 91 via a pipeline.

[0037] In the above implementation scheme, the diffusion permeation membrane 2 is backflushed by the second gas purification system as follows: the purge chamber 11 is subjected to the suction of the second gas pump 91, which removes part of the migrating gas to purge the diffusion permeation membrane 2. The gas to be tested that permeates through the diffusion permeation membrane 2 is directly discharged from the fourth gas port. The gas in the ionization chamber 13 is mostly gas purified by the second gas purification device 92. Part of the gas purified by the second gas purification device 92 enters the Faraday disk 5 through the pipeline, and the other part passes through, so the air state can be restored as soon as possible (i.e., backflushing purification is performed on the inner surface of the diffusion permeation membrane 2). At this time, valve ports A' and B' are open, and valve port C' is closed. Part of the gas enters the second gas pump 91 through the fourth gas port set on the cavity wall of the ionization chamber 13, and the other part passes through the purge chamber 11. The second gas inlet enters the second gas pump 91 through valve port B' and valve port A', and then returns to the migration chamber 14 after being purified by the second gas purification device 92. At the same time, it can work in conjunction with the first gas pump 82 (while the sampling pump 84 stops). Gas is drawn in from the external environment and purified by the first gas purification device 83. The clean airflow enters the purge chamber 11 through the first control valve 81 (valve port A and valve port B are connected) to clean the sample inlet side (i.e., the outer surface of the diffusion permeation membrane 2). Since the incoming gas has been cleaned, it can help the diffusion permeation membrane 2 to quickly desorb the residual analyte, thereby achieving rapid cleaning of the diffusion permeation membrane 2. In other words, in the backflushing mode, the inner and outer surfaces of the diffusion permeation membrane 2 are simultaneously treated, which greatly improves the purification effect.

[0038] Implementation Case 3: As a preferred implementation method, such as Figure 3 As shown, the second control valve 93 is a two-position three-way valve. One valve port (valve port B') of the two-position three-way valve is connected to the second gas port through a pipeline. The other two valve ports (valve port A' and valve port C') of the two-position three-way valve are respectively connected to the inlet of the second gas pump 91 and the outlet of the second gas purification device 92 through pipelines.

[0039] In the above implementation scheme, the second gas purification system has the following two operating states: 1) Backflush: Refer to the backflush process described above, and will not be repeated here: 2) Sampling: During operation, valve ports B' and C' of the second control valve 93 are connected (valve port A' is closed). The gas flow purified by the second gas purification device 92 enters the end of the migration chamber 14 at a certain split ratio to form migration gas. Another part enters the purge chamber 11 through valve ports C', B', and the second gas port. This gas flow is pure at this time, which is beneficial to the permeation of the gas to be measured in the diffusion permeation membrane 2 because the concentration gradient is the largest at this time, avoiding the slow response problem caused by the slow gas diffusion rate near the diffusion permeation membrane 2 in the original design. After the permeation is completed, the gas in the purge chamber 11 is accelerated into the ionization chamber 13 through the air holes of the gas guide component 7 and is quickly ionized. The funnel-shaped cavity structure formed between one end of the gas guide component 7 and the diffusion permeation membrane 2 can reduce the gas contact area and accelerate the efficiency of the gas flow into the ionization chamber 13. During backflushing, the air hole in the center of the gas guide component 7 can increase the flow rate of the incoming gas flow and improve the efficiency of purging the diffusion permeation membrane 2. The airflow entering the migration chamber 14 and the purge chamber 11 is eventually drawn away by the second air pump 91 and purified by the second gas purification device 92, forming an airflow circulation inside the migration tube 1. In the aforementioned state, the sampling pump 84 is working, the first air pump 82 is not working, and the external gas enters the sample injection chamber 12 due to the suction of the air pump, and is then discharged through the first air pump 82.

[0040] On both sides of the diffusion permeation membrane 2, airflow for active purification of the membrane is added. The sample inlet chamber 12 uses a filter to pump clean gas from ambient air. On one side of the ionization chamber 13, a purge chamber 11 is added. A second control valve 93 cleverly alters the airflow, enabling reverse purging. This allows the gas released from the diffusion permeation membrane 2 (on the ionization chamber 13 side) to be directly purified without being ionized, thus improving the recovery rate. The purge chamber 11 significantly increases the permeation rate of the diffusion permeation membrane 2, reduces local concentration, and thus improves the response speed.

[0041] It is particularly important to emphasize that the rapid recovery ion mobility spectrometry device in this embodiment is connected to a control system and an alarm circuit. Since there is no physical change in the gas path connection, the ion mobility spectrometry device can freely switch between normal operation and rapid cleaning. When the concentration of the analyte exceeds a certain threshold, it can quickly enter cleaning mode, and after basic cleaning, it can enter detection mode. Although the cleaning mode cannot detect the analyte, without entering cleaning mode, the ion mobility spectrometry device is in a contaminated state; although it draws in air from the environment, it cannot be in detection mode. After rapid cleaning, it can re-enter detection mode. If the analyte gas is no longer present in the environment, the alarm will not continue; however, if the analyte gas is still present, it can still quickly alarm due to the optimized gas path design. The alarm will not be canceled while the device is in cleaning mode until the analyte gas is not detected in detection mode or the concentration of the analyte gas is lower than the alarm value. This operating mode avoids equipment contamination caused by high concentrations of gas in the environment and can more quickly reflect changes in gas concentration. The gas concentration is monitored using conventional gas concentration sensors and other equipment connected to the control system.

[0042] It should be further explained that: In this embodiment, the sidewall of the portion of the migration tube 1 corresponding to the sample injection chamber 12 can be made of metal (aluminum alloy, stainless steel, etc.), ceramic (alumina, aluminosilicate, etc.), or anti-adsorption plastic (fluorinated resin, PEEK, polyimide, etc.), with a diameter of 1-100 mm and a length of 1-50 mm; the diffusion permeation membrane 2 (which can be a Teflon film) has a diameter of 1-100 mm and a thickness of 1-1000 μm; the ionization source 3 can be a radioactive material (Ni-63, Am-241) or a discharge ionization device (high voltage DC discharge, dielectric barrier discharge, etc.); the purge chamber 11 can be made of ceramic or plastic alternating with metal to provide voltage drop, and the metal can be aluminum alloy, stainless steel, copper, etc., with a diameter of 1-100 mm and a length of 1-100 mm; the sidewall of the portion of the migration tube 1 corresponding to the ionization chamber 13 (including the portion from the diffusion permeation membrane 2 to the ion gate 4) The ion gate 4 can be made of ceramic or plastic alternating with metal to provide voltage drop, and the metal can be aluminum alloy, stainless steel, copper, etc. Its diameter is 1-100mm, and its length is 10-100mm. The migration chamber 14 (containing the area from the ion gate to the Faraday disk) can be made of ceramic or plastic alternating with metal to provide voltage drop, and the metal can be aluminum alloy, stainless steel, copper, etc. Its diameter is 1-100mm, and its length is 10-200mm. The Faraday disk 5 is used to collect ions to form the current; its material is conductive metal, and its diameter is smaller than the inner diameter of the migration region, with a diameter of 1-100mm. The preamplifier 6 is used to convert the ion current into a detectable voltage signal. The first gas pump 82, the second gas pump 91, and the sampling pump 84 all use compatible miniature diaphragm pumps with a flow rate range of 10-1000 mL / min.

[0043] In this embodiment, both the first gas purification device 83 and the second gas purification device 92 include a tubular outer shell and a gas purification material filled in the outer shell. The gas purification material is mainly used to adsorb the water vapor and the gas to be tested that have permeated in. The optional materials are molecular sieves (optional types include 4A, 5A, 13X), activated carbon, or a composite containing one of the two).

[0044] The rapid recovery method for the ion mobility spectrometry device in this embodiment includes the following steps: Step 1: Turn on sampling pump 84 for sampling (the sampling status is described in the above embodiment and will not be repeated here). Step 2: The ion mobility spectrometer synchronously monitors the concentration of the gas to be measured at the diffusion permeation membrane (the ion mobility spectrometer has its own concentration monitoring function, which is a traditional function of the device and will not be described in detail here). If the concentration is lower than the set threshold, sampling continues. If the concentration is not lower than the set threshold, the alarm of the ion mobility spectrometer will continue to sound. After the alarm time period t1, it switches to the backflushing state (refer to the description in the previous embodiment, which will not be described in detail here). Backflushing is performed synchronously on both sides of the diffusion permeation membrane 2. After the backflushing continues for time period t2, it switches to the sampling state. Step 3: In the sampling state, if the concentration of the gas being measured does not exceed the set threshold within the time period t3, the alarm will stop; otherwise, switch to the backflushing state to continue purging until the concentration of the gas being measured does not exceed the set threshold within the time period t3 in the sampling state.

[0045] Among them, t1 ranges from 1 to 10 s, t2 ranges from 5 to 20 s, and t3 ranges from 2 to 4 s.

[0046] Taking dimethyl methylphosphonate (DMMP) as the gas to be tested, when the sampling flow rate is 500 mL / min, and 10 mg / m³ is introduced... 3 The methyl methyl phosphonate (DMMP) is stopped after 30 seconds. At this time, the air migration peak completely disappears. The reacting ions and DMMP form a mass migration peak. If the purge gas path is not switched, it will take 20 minutes for the air peak to recover to 80% intensity. If the purge is turned on, the purge will start at the third second after the sample is injected and continue for 20 seconds before switching back to the sampling state. Then, the sampling will be performed for another 3 seconds before the purge starts. This process is repeated. After 2 minutes, the air peak can be recovered to 80% intensity.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0051] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0052] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A fast recovery ion mobility spectrometry device comprising a migration tube (1), a diffusion permeable membrane (2), an ionization source (3), an ion gate (4) and a Faraday plate (5) are sequentially and spaced apart in the migration tube (1) from one end to the other end, the migration tube (1) is provided with a preamplifier (6), a purge cavity (11) is defined between the diffusion permeable membrane (2) and the ionization source (3), an injection cavity (12) is defined at the end of the diffusion permeable membrane (2) away from the ionization source (3), an ionization cavity (13) is defined between the ionization source (3) and the ion gate (4), and a migration cavity (14) is defined between the ion gate (4) and the Faraday plate (5), characterized in that: The migration tube (1) is connected with a gas purification and delivery system for delivering clean gas to the sample inlet cavity (12) and the purge cavity (11) respectively and purging gas at both ends of the diffusion permeation membrane (2).

2. The fast recovery ion mobility spectrometry device of claim 1, wherein: The sample inlet cavity (12) is provided with a first gas port communicating with the inside of the sample inlet cavity (12), the purge cavity (11) is provided with a second gas port communicating with the inside of the purge cavity (11), and the migration cavity (14) is provided with a third gas port at the end away from the ion gate (4). The gas purification and delivery system comprises a first gas purification and delivery system and a second gas purification and delivery system. The first gas port is connected with the first gas purification system, and the second gas port and the third gas port are respectively connected with the second gas purification system. The first gas purification system is used for outputting purified gas into the sample inlet cavity (12) and purging one end of the diffusion permeation membrane (2). The second gas purification system is used for delivering purified gas through the third gas port and discharging from the second gas port, thereby purging the other end of the diffusion permeation membrane (2).

3. A fast recovery ion mobility spectrometry device according to claim 2 or 3, characterized in that: The second gas purification system comprises a second gas pump (91), a second gas purification device (92) and a second control valve (93). The ionization cavity (13) is provided with a fourth gas port. The inlet of the second gas pump (91) is connected with the fourth gas port through a pipeline. The outlet of the second gas pump (91) is connected with the inlet of the second gas purification device (92) through a pipeline. The outlet of the second gas purification device (92) is connected with the third gas port through a pipeline. The second gas port is connected with the valve port of the second control valve (93) through a pipeline. The valve port of the second control valve (93) is connected with the inlet of the second gas pump (91) through a pipeline.

4. The fast recovery ion mobility spectrometer of claim 3, wherein: Further comprising a gas guide member (7) which is arranged in the purge cavity (11) and is sealingly connected with the inner wall of the migration tube (1). The gas guide member (7) is provided with a gas hole penetrating through both ends thereof at the center thereof.

5. The fast recovery ion mobility spectrometer of claim 4, wherein: The gas guide member (7) is provided with a conical gas guide cavity at the end close to the diffusion permeation membrane (2). The center of the gas guide cavity communicates with the gas hole.

6. The fast recovery ion mobility spectrometer of claim 4, wherein: The gas guide member (7) is a metal piece, a ceramic piece or an anti-adsorption plastic piece.

7. The fast recovery ion mobility spectrometer of claim 4, wherein: The gas guide member (7) is provided with a heating device for heating the gas passing through the gas hole.

8. The fast recovery ion mobility spectrometer of claim 4, wherein: The first gas purification system comprises a first control valve (81), a first gas pump (82) and a first gas purification device (83). The outlet of the first gas pump (82) is connected with the inlet of the first gas purification device (83) through a pipeline. The outlet of the first gas purification device (83) is connected with the valve port of the first control valve (81) through a pipeline. The valve port of the first control valve (81) is connected with the first gas port through a pipeline.

9. The fast recovery ion mobility spectrometry device of claim 8, wherein: Further comprising a sampling pump (84). The first control valve (81) is a two-position three-way valve. One valve port of the two-position three-way valve is connected with the outlet of the first gas purification device (83) through a pipeline. The other two valve ports of the two-position three-way valve are respectively connected with the first gas port and the inlet of the sampling pump (84) through pipelines.

10. A method of fast recovery of an ion mobility spectrometry device as defined in claim 9, characterized in that, The method comprises the following steps: Step one, starting the sampling pump (84) to sample; Step two, the ion mobility spectrometry device synchronously monitors the concentration of the measured gas at the diffusion permeation membrane (2), if the concentration is lower than the set threshold, the sampling continues, if the concentration is not lower than the set threshold, the alarm of the ion mobility spectrometry device continues to alarm, after the alarm t1 time period, it is switched to the back flushing state, and the diffusion permeation membrane (2) is synchronously back flushed on both sides, after the back flushing lasts for t2 time period, it is switched to the sampling state; Step three, in the sampling state, if the concentration of the measured gas does not exceed the set threshold within t3 time period, the alarm is stopped; otherwise, it is switched to the back flushing state to continue to purge until the concentration of the measured gas does not exceed the set threshold within t3 time period in the sampling state.

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