Method for inhibiting influence of humidity on ion mobility spectrometry signal response

Abstract

The invention discloses a method for inhibiting the influence of humidity on ion mobility spectrometry signal response, which can greatly reduce the number density of water molecules in an ionization region and reduce the competitive absorption of photons by the water molecules by reducing the working air pressure in an ion mobility spectrometry migration tube and / or increasing the working temperature in the ion mobility spectrometry migration tube. Moreover, dissociation of ion clusters of water molecules and target compound molecules is promoted, false alarm of product ion mobility is avoided, and the influence of humidity on ion mobility spectrum signal response is inhibited. The method has the advantages of low difficulty in air pressure and temperature regulation and control, easiness in operation, high universality, no need of sample pretreatment, capability of monitoring a high-humidity sample on line in real time, and inhibition of the influence of humidity on ion signal response of a target compound.

Description

Technical Field

[0001] The present invention belongs to the field of analytical chemical instruments, and specifically relates to regulating the gas pressure conditions and temperature regulation in an ion mobility spectrometer migration tube to reduce the competitive absorption of photons by water molecules and the dissociation of water molecule clusters of product ions when analyzing a 100% RH sample, thereby inhibiting the negative impact of high humidity on the ion mobility spectrometer signal response. Background Art

[0002] The origin of ion mobility spectrometry (IMS) can be traced back to the mid-1960s. It is a separation and analysis technique that characterizes substances based on the difference in ion migration rates of different ions in the gas phase under the action of an electric field. However, humidity interference is a serious problem for ion mobility spectrometry. When humidity increases, water molecules in the air will combine with sample molecules or ionizing agent molecules to form hydrated ions or cluster ions. The formation of these hydrates will change the mass and volume of the ions, thereby affecting the ion migration time and sensitivity, leading to deviations in the results.

[0003] A positive ion mobility spectrometry detection method for propofol in exhaled air invented by Jiang Dandan et al. (patent number CN109781827A) eliminates the interference of sevoflurane and humidity in exhaled air in compound anesthesia by using reagent molecule-assisted photoionization positive ion mobility spectrometry technology, combined with a time-resolved dynamic dilution sampling device, and realizes clinical continuous online monitoring of propofol in exhaled air. However, this method requires the exhaled air carrier to enter the sampling loop first, and then the various compounds remaining in the sampling loop are dynamically diluted and sent to the ion mobility spectrometer for detection by carrier gas purge. This method cannot realize online real-time analysis of samples, and the interference of humidity removal by the sampling loop will inevitably bring about the influence of memory effect. A pre-enrichment device for ion mobility spectrometry invented by Jiang Dandan et al. (patent number CN213875525U) solves the problem of humidity interference and low sensitivity for the detection of high-humidity samples in the environment by combining a dehumidifying membrane separator and a sample enrichment filling column. However, the pre-separation of environmental samples will cause the response time of IMS to be longer, and it is also impossible to monitor the target analyte in real time online.

[0004] Zhou Qinghua et al. (Talanta, 2012, 98; Analytical Methods, 2014, 6; Journal of Breath Research, 2015, 9) solved the problem of the influence of high humidity in exhaled breath on propofol detection by using constant temperature membrane injection, enrichment-analysis membrane injection, and time-resolved dynamic dilution injection. In addition, chromatography-mass spectrometry can also effectively solve the influence of high humidity in environmental samples on the detection of target compounds, but it has the disadvantages of high cost, large volume, and the need for specialized technicians to operate.

[0005] In order to suppress the negative impact of humidity on the detection results in the detection of high-humidity target samples, the present invention reduces the working air pressure in the ion mobility spectrometry migration tube and increases the working temperature, which can not only significantly reduce the number density of water molecules in the ionization zone, reduce the competitive absorption of photons by water molecules, but also promote the dissociation of water molecules and target compound molecular ion clusters, avoiding false positives in product ion mobility. The present invention has low difficulty in regulating air pressure, is easy to operate, has strong universality, does not require sample pretreatment, can monitor high-humidity samples online in real time, and completely suppresses the influence of humidity on the ion signal response of the target compound. Summary of the invention

[0006] The object of the present invention is to provide a method for suppressing the influence of humidity on the signal response of ion migration spectrometry. The method utilizes the reduction of the number density of water molecules in the ionization zone under low pressure conditions to reduce the competitive absorption of photons, and the cluster ions formed by the target analyte ions and the water molecules are also dissociated under low pressure conditions, thereby suppressing the negative influence of high humidity conditions on the signal response of the target analyte; similarly, when the working temperature in the migration tube is increased, it is not conducive to the stability of the clusters formed by the water molecules and the target to be measured, and the water molecule clusters are dissociated by increasing the kinetic energy of the ions, so as to achieve the negative influence of water molecules on signal detection when detecting the target analyte with high humidity.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: a method for suppressing the influence of humidity on the response of ion mobility spectrometry signal, the method is specifically:

[0008] 1) adjusting the working gas pressure of the ion mobility spectrometer to be in the range of 10 to 100 kPa, preferably 10 to 50 kPa, more preferably 10 to 30 kPa;

[0009] and / or, 2) maintaining the working temperature in the migration tube in the range of 40-120°C, preferably 50-100°C, more preferably 80-100°C.

[0010] The ion mobility spectrometer comprises an ion mobility tube, wherein an ion source, an ionization zone, an ion gate, a mobility zone and an ion receiving electrode are sequentially arranged from left to right along the axial direction of the ion mobility tube; an air inlet is arranged on the upper wall of the ionization zone near one end of the ion source; the air inlet is connected to a carrier gas source through a reagent molecule headspace purge device, an ultrapure water humidification device and a first mass flowmeter sequentially arranged on a connecting pipeline, and the first mass flowmeter controls the carrier gas with a fixed flow rate to carry the reagent molecules in the reagent molecule headspace purge device into the air inlet of the ion mobility tube;

[0011] An outlet is provided at one end of the ionization zone near the ion gate, and the outlet is connected to the atmosphere through a barometer, a needle valve and a mechanical pump arranged in sequence on the connecting pipeline. A drift gas inlet is provided above the ion receiving electrode on the right wall of the migration zone, and the drift gas inlet is connected to the drift gas source through a second mass flow meter.

[0012] The ultrapure water humidifying device is a closed container filled with ultrapure water. An air inlet and an air outlet are arranged on the top of the container. One end of a connecting pipe enters below the ultrapure water surface through the air inlet, and the other end of the connecting pipe is connected to a carrier gas source through a first mass flow meter. The air outlet of the ultrapure water humidifying device is connected to a reagent molecule headspace purge device through a connecting pipe fixed to the air outlet.

[0013] The reagent molecule headspace purge device comprises a sealed container and a reagent bottle with an upper opening placed in the sealed container, wherein the reagent bottle is filled with reagent molecules; a carrier gas inlet and a reagent molecule outlet are respectively arranged on the sealed container on the left and right sides of the reagent bottle; the carrier gas inlet is connected to a carrier gas source through an ultrapure water humidifying device and a first mass flowmeter, and the reagent molecule outlet is connected to an ion migration tube inlet through a pipeline.

[0014] A heating and heat preservation unit is arranged on the outer wall of the ion transfer tube; the heating and heat preservation unit is composed of insulating high temperature resistant heat preservation material, a heating plate and a temperature controller, and is used for heating and heat preservation of the ion transfer tube, and can keep the temperature of the ion transfer tube at a certain temperature between 30-200°C, and the temperature control deviation is less than 0.5°C.

[0015] The method for adjusting the working gas pressure of the ion mobility spectrometer is to change the exhaust flow rate of the gas outlet (8) by adjusting the needle valve (10), and to ensure that the working gas pressure of the ion mobility tube is within the range of 10 to 100 kPa, preferably 10 to 50 kPa, and more preferably 10 to 30 kPa by reading the indicated value of the barometer (9);

[0016] When the ion mobility spectrometer is working, the working temperature in the ion mobility tube is maintained in the range of 40-120°C, preferably 50-100°C, more preferably 80-100°C by controlling the heating and heat preservation unit.

[0017] When the ion transfer tube is working, when the air pressure and temperature conditions are stable, a drift gas enters the interior of the transfer zone from the drift gas inlet set on the transfer zone, and flows out of the ion transfer tube through the ion transfer tube outlet in the direction opposite to the ion flight direction; the sample gas to be tested is purged by clean compressed air through an ultrapure water device to obtain a high humidity sample of 100% RH, and enters the ionization zone of the transfer tube through the ion transfer tube inlet and is first ionized; then the product ions enter the transfer zone through the periodically opened ion gate, and reach the ion receiving electrode in succession under the drive of the electric field inside the transfer zone, and are converted into a spectrum information output of current intensity versus time.

[0018] The needle valve was adjusted to stabilize the gas pressure in the migration tube to 100, 90, 80, 70, 60, 50, 40, 30, 20 and 10 kPa, respectively, and the spectral information of 100% RH samples and 0% RH under multiple gas pressure conditions was recorded.

[0019] Under the optimized gas pressure conditions, the temperature control module was adjusted to set the working temperatures in the migration tube to 30 and 100°C, respectively, and stabilized at the set temperature conditions for about 1 hour to make the temperature field in the migration tube more uniform.

[0020] In order to ensure high-throughput detection of ion mobility spectrometry, under the control of the first mass flowmeter, the flow rate range of the migration tube inlet is 10-100mL / min, and under the control of the second mass flowmeter, the flow rate range of the drift gas inlet is 20-150mL / min.

[0021] The ionization source is any one of a radioactive ionization source, an electrospray ionization source, a corona discharge ion source, and a photoionization source into which dopants are introduced.

[0022] The ion gate is any one of a Tyndall-Powell type ion gate and a Bradbury-Nielsen type ion gate.

[0023] The present invention adjusts the working gas pressure and working temperature in the migration tube to reduce the competitive absorption of photons by water molecules and the dissociation of water molecule clusters of product ions when analyzing 100% RH samples, thereby suppressing the negative impact of high humidity on the ion mobility spectrometry signal response. The method does not require sample pretreatment, has low cost, fast analysis speed, and is universal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1. A schematic diagram of an ion migration spectrometer structure for regulating gas pressure. Including: 1. ion source; 2. air inlet; 3. first mass flowmeter; 4. ultrapure water humidification device; 5. reagent molecule headspace purge device; 6. floating gas inlet; 7. second mass flowmeter; 8. air outlet; 9. barometer; 10. needle valve; 11. mechanical pump; 12. ion receiving electrode; 13. ionization zone; 14. migration zone; 15. ion gate. Figure 2 .Ion migration spectra of 2ppmv acetone sample gas under 100%RH and 0%RH conditions at 100kPa pressure.

[0025] Figure 3 Ion mobility spectra of 2ppmv acetone sample gas at 100%RH and 0%RH under 50kPa pressure.

[0026] Figure 4 Ion migration spectra of 2ppmv acetone sample gas at 100%RH and 0%RH under 20kPa pressure.

[0027] Figure 5 .In the gas pressure range of 10 to 100 kPa, the ratio of the peak areas of the acetone sample gas with a concentration of 2 ppmv under 100% RH and 0% RH conditions changes with the gas pressure.

[0028] Figure 6 Ion mobility spectra of 2ppmv acetone sample gas at 100%RH and 20kPa pressure at 30℃ and 100℃ migration tube temperatures. DETAILED DESCRIPTION

[0029] An ion mobility spectrometer structure for suppressing the influence of humidity on the ion mobility spectrometer signal response is as follows: Figure 1 As shown, the ion mobility spectrometer includes an ion mobility tube, which is a mobility tube with good air tightness, and an ion source 1, an ionization region 13, an ion gate 15, a mobility region 14 and an ion receiving electrode 12 are sequentially arranged along the axial direction of the ion mobility tube from left to right; an air inlet 2 is arranged on the upper wall of the ionization region 13 near one end of the ion source 1; the air inlet 2 is connected to the carrier gas source through a reagent molecule headspace purge device 5, an ultrapure water humidification device 4 and a first mass flowmeter 3 sequentially arranged on the connecting pipeline, and the first mass flowmeter 3 controls the carrier gas with a fixed flow rate, and carries the reagent molecules in the reagent molecule headspace purge device 5 into the air inlet 2 of the ion mobility tube;

[0030] An air outlet 8 is provided at one end of the ionization region 13 near the ion gate 15, and the air outlet 8 is connected to the atmosphere through a barometer 9 and a needle valve 10 and a mechanical pump 11 which are sequentially arranged on the connecting pipeline; a floating gas inlet 6 is provided above the ion receiving electrode 12 on the right wall of the migration region 14; the floating gas inlet 6 is connected to the floating gas source through a second mass flow meter 7,

[0031] The ultrapure water humidifying device 4 is a closed container filled with ultrapure water. An air inlet and an air outlet are provided on the top of the container. One end of a connecting pipe enters below the ultrapure water surface through the air inlet, and the other end of the connecting pipe is connected to the carrier gas source through the first mass flow meter 3. The air outlet of the ultrapure water humidifying device 4 is connected to the reagent molecule head space purge device 5 through a connecting pipe fixed to the air outlet.

[0032] The reagent molecule headspace purge device 5 comprises a sealed container and a reagent bottle with an upper opening placed in the sealed container, and the reagent bottle is filled with reagent molecules; a carrier gas inlet and a reagent molecule outlet are respectively arranged on the sealed container on the left and right sides of the reagent bottle; the carrier gas inlet is connected to the carrier gas source through the ultrapure water humidification device 4 and the first mass flowmeter 3, and the reagent molecule outlet is connected to the ion migration tube inlet 2 through a pipeline.

[0033] A heating and heat preservation unit is provided on the outer wall of the ion transfer tube; the heating and heat preservation unit is composed of insulating high temperature resistant heat preservation material, a heating plate and a temperature controller, and is used for heating and heat preservation of the ion transfer tube, and can maintain the temperature of the ion transfer tube at a certain temperature between 30-200°C, and the temperature control deviation is less than 0.5°C;

[0034] The ion source 1 adopts a vacuum ultraviolet lamp; the ion gate is a Tyndall-Powell type ion gate.

[0035] The floating gas source and the carrier gas source are clean compressed air, and the clean compressed air is air filtered through 13X molecular sieve and activated carbon in sequence.

[0036] All the inlet and outlet pipes are connected, and the pressure condition in the migration tube is controlled by the flow meter 3 for controlling the velocity of the sample gas and the drift gas and the needle valve 10 at the front end of the mechanical pump 11. The working temperature in the migration tube is adjusted by the heating and heat preservation unit arranged on the outer wall of the migration tube.

[0037] Comparative Example 1

[0038] The electric field strength of the fixed ionization zone 13 is 450V / cm, and the electric field strength of the migration zone is 400V / cm. The needle valve is adjusted to stabilize the pressure in the migration tube at 100kPa, and the barometer is read. The heating and insulation unit is controlled to fix the working temperature of the ion migration tube at 30°C. The drift gas flow rate is fixed at 150mL / min. The 2ppmv acetone standard gas is introduced into the ionization zone through the ultrapure water humidification device at an inlet flow rate of 50mL / min and ionized by the vacuum ultraviolet light. After that, the product ions are introduced into the migration zone by the electric field and reach the ion receiving electrode to be detected. Record the ion migration spectrum of 100%RH acetone standard gas at 30°C under 100kPa pressure conditions, as shown in FIG. Figure 2 As shown,

[0039] Then remove the ultrapure water humidification device and repeat the above steps to record the ion migration spectrum of 0% RH acetone standard gas, such as Figure 2 As shown. It can be found that when the ion migration tube is under the pressure of 100 kPa and the working temperature is 30°C, the signal response of the acetone standard gas ion spectrum peak under 100% RH is greatly suppressed. At room temperature and pressure, humidity seriously affects the detection sensitivity of the reagent molecule acetone dimer ion, and the high humidity environment will cause the acetone dimer ion to cluster with more water molecules, thereby reducing the ion mobility K and the migration time t d The backward movement affects the accuracy of IMS detection.

[0040] Example 1

[0041] The drift gas flow rate was fixed at 150 mL / min, the sample inlet gas flow rate was 50 mL / min, the electric field strength of the ionization zone 13 was fixed at 450 V / cm, and the electric field strength of the migration zone was fixed at 400 V / cm. The needle valve 9 before the mechanical pump 10 was adjusted to stabilize the working pressure in the ion migration tube at 50 kPa. The heating and insulation unit was controlled to fix the working temperature of the ion migration tube at 30 ° C. The drift gas entered the migration zone from the drift gas inlet set on the migration zone, and flowed out of the ion migration tube through the gas outlet in the direction opposite to the flight direction of the ions. ion migration tube; 2ppmv acetone sample gas is purged by clean compressed air through an ultrapure water device to obtain a high humidity 2ppmv acetone sample of 100%RH, which enters the ionization zone of the migration tube through the air inlet and is first ionized; then the product ions enter the migration zone through the periodically opened ion gate, and under the drive of the internal electric field of the migration zone, they successively reach the ion receiving electrode and are converted into a spectrum information output of current intensity versus time, and a 2ppmv acetone molecular spectrum of 100%RH at 30°C and 50kPa pressure is obtained, as shown in FIG. Figure 3 As shown;

[0042] After removing the ultrapure water humidification device, the 0%RH 2ppmv acetone sample gas is ionized by clean compressed air entering the ionization zone of the migration tube through the air inlet and introduced into the migration zone to reach the ion receiving electrode, and is converted into a spectrum information output of current intensity versus time, and a 0%RH 2ppmv acetone molecular spectrum at 30°C and 50kPa pressure is obtained, as shown in the figure. Figure 3 shown.

[0043] Depend on Figure 2 and Figure 3 By comparison, it can be seen that lowering the working gas pressure of the ion migration tube can suppress the negative impact of humidity on the sample detection signal response.

[0044] Example 2

[0045] The drift gas flow rate was fixed at 150 mL / min, the sample inlet gas flow rate was 50 mL / min, the electric field strength of the ionization zone 13 was fixed at 450 V / cm, and the electric field strength of the migration zone was fixed at 400 V / cm. The needle valve 9 before the mechanical pump 10 was adjusted to stabilize the working pressure in the ion migration tube at 20 kPa. The heating and insulation unit was controlled to fix the working temperature of the ion migration tube at 30° C. The other detection processes were the same as in Example 1. The spectra of 2 ppmv acetone molecules at 100% RH and 0% RH were recorded respectively, as shown in FIG. Figure 4 shown.

[0046] Combination Figure 2 and Figure 4 The results show that when the working temperature of the migration spectrometer is fixed at 30°C, it can be found that lowering the working gas pressure of the ion migration tube to 20 kPa can effectively suppress the negative impact of humidity on the signal response of sample detection.

[0047] Example 3

[0048] The drift gas flow rate was fixed at 150 mL / min, the sample inlet gas flow rate was 50 mL / min, the electric field strength of the fixed ionization zone 13 was 450 V / cm, the electric field strength of the migration zone was 400 V / cm, the heating and insulation unit was controlled to fix the working temperature of the ion migration tube at 30°C, the needle valve 9 before the mechanical pump 10 was adjusted to stabilize the working pressure in the ion migration tube at 100, 90, 80, 70, 60, 50, 40, 30, 20 and 10 kPa, respectively. The other detection processes were the same as in Example 1, and the records were respectively The migration spectra of 2ppmv acetone sample gas under 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20% and 10kPa conditions were recorded, and the peak area of ​​acetone dimer ion obtained under each experimental condition was integrated, so as to calculate the variation trend of the ratio of the peak area of ​​acetone dimer ion obtained under 100%RH and 0%RH conditions under different gas pressures with gas pressure, so as to compare and illustrate the effect of different gas pressure conditions on the suppression of humidity on the response of ion mobility spectrometry signal, such as Figure 5 shown.

[0049] It can be found that the lower the working pressure of the ion transfer tube is in the range of 10-100 kPa, the smaller the negative impact of humidity on the signal response is. At 10 kPa, the signal response of 100% RH is only reduced by ~10% compared with 0% RH.

[0050] Example 4

[0051] The drift gas flow rate was fixed at 150 mL / min, the sample inlet gas flow rate was 50 mL / min, the electric field strength of the ionization region 13 was fixed at 450 V / cm, the electric field strength of the migration region was fixed at 400 V / cm, the working pressure condition in the ion migration spectrum was fixed at 20 kPa, the heating and heat preservation unit of the migration tube was adjusted to stabilize the working temperature in the ion migration tube at 30° C. and 100° C., respectively. The other detection conditions were the same as those in Example 1, and the ion migration spectra of the 2 ppmv acetone sample gas at 100% RH and 0% RH were recorded, respectively, as shown in FIG. Figure 6 As shown, it can be found that when the working gas pressure in the migration tube is fixed, the increase in working temperature can effectively suppress the negative impact of humidity on the signal response of sample detection.

Claims

1. A method for suppressing the effect of humidity on ion mobility spectrometry signal response, characterized in that: The method is specifically as follows: 1) adjusting the working gas pressure of the ion mobility spectrometer to be in the range of 10 to 100 kPa, preferably 10 to 50 kPa, more preferably 10 to 30 kPa; and / or, 2) maintaining the working temperature in the migration tube in the range of 40-120°C, preferably 50-100°C, more preferably 80-100°C.

2. The method for suppressing the influence of humidity on the ion mobility spectrometry signal response according to claim 1, characterized in that: The ion mobility spectrometer comprises an ion mobility tube, wherein an ion source (1), an ionization region (13), an ion gate (15), a mobility region (14) and an ion receiving electrode (12) are sequentially arranged along the axial direction of the ion mobility tube from left to right; an air inlet (2) is arranged on the upper wall of the ionization region (13) close to one end of the ion source (1); the air inlet (2) is connected to a carrier gas source through a reagent molecule headspace purge device (5), an ultrapure water humidification device (4) and a first mass flowmeter (3) sequentially arranged on a connecting pipeline, and the first mass flowmeter (3) controls the carrier gas with a fixed flow rate to carry the reagent molecules in the reagent molecule headspace purge device (5) into the air inlet (2) of the ion mobility tube; An air outlet (8) is provided at one end of the ionization region (13) near the ion gate (15), and the air outlet (8) is connected to the atmosphere through a barometer (9), a needle valve (10) and a mechanical pump (11) which are sequentially arranged on a connecting pipeline. A floating gas inlet (6) is provided above the ion receiving electrode (12) on the right wall of the migration region (14), and the floating gas inlet (6) is connected to a floating gas source through a second mass flow meter (7). The ultrapure water humidifying device (4) is a sealed container containing ultrapure water. An air inlet and an air outlet are provided on the top of the container. One end of a connecting pipe extends below the ultrapure water surface through the air inlet. The other end of the connecting pipe is connected to a carrier gas source through a first mass flow meter (3). The air outlet of the ultrapure water humidifying device (4) is connected to a reagent molecule headspace purge device (5) through a connecting pipe fixed to the air outlet. The reagent molecule headspace purge device (5) comprises a sealed container and a reagent bottle with an upper end opened and placed in the sealed container, wherein the reagent bottle is filled with reagent molecules; a carrier gas inlet and a reagent molecule outlet are respectively arranged on the sealed container on the left and right sides of the reagent bottle; the carrier gas inlet is connected to a carrier gas source through an ultrapure water humidifying device (4) and a first mass flowmeter (3), and the reagent molecule outlet is connected to an ion migration tube inlet (2) through a pipeline. A heating and heat preservation unit is provided on the outer wall surface of the ion migration tube; The heating and heat preservation unit is composed of insulating high temperature resistant heat preservation material, heating plate and temperature controller, and is used for heating and heat preservation of ion migration tube. The temperature of ion migration tube can be kept at a certain temperature between 30-200℃, and the temperature control deviation is less than 0.5℃.

3. The method for suppressing the influence of humidity on the ion mobility spectrometry signal response according to claim 1 or 2, characterized in that: The method for adjusting the working gas pressure of the ion mobility spectrometer is to change the exhaust flow rate of the gas outlet (8) by adjusting the needle valve (10), and to ensure the working gas pressure of the ion mobility tube by reading the indicated value of the barometer (9); When the ion mobility spectrometer is working, the working temperature in the ion mobility tube is maintained by controlling the heating and heat preservation unit.

4. The method for suppressing the influence of humidity on the ion mobility spectrometry signal response according to claim 1 or 2, characterized in that: The ion source (1) is any one of a radioactive ionization source, an electrospray ionization source, a corona discharge ion source, and a dopant-introduced photoionization source.

5. The method for suppressing the influence of humidity on the ion mobility spectrometry signal response according to claim 1 or 2, characterized in that: The flow rate range of the gas inlet of the ion transfer tube is 10-100 mL / min, and the flow rate range of the drift gas inlet is 20-150 mL / min.

6. The method for suppressing the influence of humidity on the response of ion mobility spectrometry signal according to claim 1 or 2, characterized in that: The ion gates used are Tyndall-Powell type ion gate and Bradbury-Nielsen type ion gate.

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