Trace detection method and device for sulfur-containing sample

Abstract

The invention provides a method and a device for quickly and sensitively detecting a trace amount of sulfur-containing sample on site. The method comprises the following steps: adopting a Fourier deconvolution multiplexing ion mobility spectrometry technology, a negative ion mode and a thermal desorption sampling mode, and ensuring that migration gas and carrier gas do not need any chloride additive; an analysis method for directly separating an air reagent ion peak (O2 (H2O) n) and a sulfur product ion peak through ion mobility spectrometry and effectively separating sulfur-containing samples and nitrogen-containing samples such as black powder is established. According to the invention, the resolution ratio of the air reagent ion peak can be improved, the separation degree of a compound which is very close to the migration time of the air reagent ion peak can be improved, the effective separation of sulfur-containing samples such as black powder from the air reagent ion peak can be realized, and the analysis and recognition capability of the ion mobility spectrometry on the sulfur-containing samples such as black powder and nitrogen-containing samples can be improved.

Description

Technical Field

[0001] The invention belongs to the field of trace detection instruments, and in particular relates to a trace detection method and device for sulfur-containing samples. Background Art

[0002] Ion Mobility Spectrometry (IMS) appeared in the 1970s. It is a rapid detection and analysis technology in which the molecular ions of a compound collide with neutral gas molecules in a uniform electric field and separate at different rates at normal pressure. IMS is widely used in the fields of explosives, chemical warfare agents, drug detection, environmental monitoring, water pollution monitoring and toxic gas monitoring due to its fast detection speed, high sensitivity, reliable structure, simple structure, small size and low analysis cost.

[0003] Black powder, gun ammunition and firecrackers are explosives containing sulfur, and explosives are explosive, destructive and lethal, which can pose a threat and hazard to public safety. In recent years, terrorist bombings have occurred from time to time around the world, and various forms of explosives have been used in terrorist criminal activities. Black powder and nitrogen-containing explosives such as trinitrotoluene (TNT) are often used by terrorists because of their strong explosive power and low price. In order to prevent the occurrence of terrorist bombings, many countries and departments are developing fast, sensitive and accurate methods to detect hidden trace explosives.

[0004] Conventional ion mobility spectrometry usually has a low resolution. When it comes to detecting explosives, it is not possible to detect trace amounts of sulfur-containing samples such as black powder because the product ion peaks of sulfur-containing samples such as black powder overlap with the air reagent ion peak (O2 − (H2O) n ) overlap, so they cannot be detected directly.

[0005] At present, there are many patents on ion mobility spectrometry detection of explosives, especially for the detection of sulfur-containing samples such as black powder. For example, Li Haiyang et al. have been granted a patent application (CN103884770 B), which is a method for detecting explosives. Carbon tetrachloride is added as an additive to the migration gas of the ion mobility spectrometer. The excess air reagent ions ( ) are chemical additives with shorter migration times, chloride ions ( ) to avoid overlap, so that the product ion peaks of sulfur-containing samples such as black powder are separated from the chloride ion peaks of chemical additives; for example, Wang Xin et al. (201210222589.0) announced the application of chlorinated hydrocarbon compounds in ion mobility spectrometry detection of explosives, and introduced the rapid self-cleaning function of dichloromethane to achieve the separation and detection of chloride ion peaks of chemical additives and sulfur-containing samples such as black powder.

[0006] In addition, in the currently disclosed methods for detecting explosives such as black powder, chemical additives are generally added to the migration gas, carrier gas or circulating gas path to achieve separation and analysis of sulfur-containing samples such as black powder. Although the separation degree can be increased by adding chemical additives to the migration tube, it will increase the complexity of the detection device, and the additives need to be checked regularly, which will increase the cost and volume of the explosive detection device; it is not conducive to the miniaturization or portability of the explosive detection device, and it is difficult to detect explosives on-site, quickly and sensitively. Summary of the invention

[0007] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a trace detection method and device for sulfur-containing samples, which realizes the effective separation of sulfur-containing samples such as black powder and air reagent ion peaks, improves the separation degree and sensitivity of ion mobility spectrometry for sulfur-containing samples such as black powder and nitrogen-containing samples, and has low cost, easy implementation and high resolution.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] The first aspect of the present invention provides a trace detection method for sulfur-containing samples, which comprises: using Fourier deconvolution multiplexing technology to detect the ion mobility spectrum of the sulfur-containing sample, using purified air as a migration gas and a carrier gas, and the Fourier deconvolution ion mobility spectrum can improve the resolution of the air reagent ion peak and the product ion peak of the sulfur-containing sample, thereby increasing the separation degree between the peak and the product ion peak of the sulfur-containing sample. The separation degree and sensitivity of the detection are further improved by adjusting the humidity of the migration gas and the carrier gas.

[0010] Furthermore, the Fourier deconvolution multiplexing technology refers to the steps of performing Fourier deconvolution on the gated modulated pulse signal that multiplexes the ion gate and the composite ion current signal collected by the detector to obtain an ion migration spectrum.

[0011] Furthermore, the purified air is air purified by using one or more of silica gel, activated carbon, and molecular sieve as migration gas and carrier gas, and no chloride additives are added to change the air peak position.

[0012] Furthermore, the sulfur-containing sample is black powder, gun ammunition or firecrackers, and the nitrogen-containing sample is TNT, ANFO, RDX or PETN.

[0013] A second aspect of the present invention provides a trace detection device for sulfur-containing samples, which comprises: a multiplexed ion gate control unit, an ionization source, a migration tube, a migration tube high-voltage control unit, a thermal desorption sample introduction unit, an amplifier, and a Fourier deconvolution ion mobility spectrometer control unit;

[0014] The multiplexed ion gate control unit is used for multiplexed control of ion gates;

[0015] The Fourier deconvolution ion mobility spectrometer control unit also includes a detection mode control unit;

[0016] The detection mode control unit is used to adjust the detection mode;

[0017] The migration tube also includes a Faraday disk for detecting multiplexed ion flow signals;

[0018] The amplifier is used to amplify the detected multiplexed ion flow signal by a certain multiple;

[0019] The thermal desorption sample introduction unit comprises a carrier gas inlet, a carrier gas and sample gas outlet, a thermal desorption chamber, a gas extraction port and an organic silicon membrane;

[0020] The thermal desorption chamber is used to analyze the sample to be detected;

[0021] Furthermore, the ionization source is a corona discharge, high-energy photoionization, a nickel source, a dielectric barrier discharge, a secondary electrospray or an ultraviolet lamp ionization source.

[0022] Furthermore, the multiplexed ion gate control unit includes an input control terminal and an output high voltage terminal, the input control terminal is connected to the Fourier deconvolution ion mobility spectrometer control unit, and the output high voltage terminal is connected to the ion gate.

[0023] Furthermore, the detection mode control unit includes one or more of a positive ion mode, a negative ion mode or a positive / negative polarity fast switching mode.

[0024] Furthermore, the migration tube also includes an injection port, which is connected to the thermal desorption sample introduction unit.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] For traditional signal averaging ion mobility spectrometers, since the resolution of signal averaging ion mobility spectrometry is usually low, when detecting sulfur-containing samples such as black powder, the product ion peak (PIP) of the sulfur-containing sample completely or partially overlaps with the air reagent ion peak (RIP), so trace amounts of sulfur-containing samples such as black powder cannot be detected. The invention adopts Fourier deconvolution multiplexed ion mobility spectrometry technology and thermal desorption sampling mode to gasify sulfur contained in sulfur-containing samples such as black powder, and does not add any chloride additives to the migration gas and the carrier gas, thereby realizing direct separation of air reagent ion peaks and sulfur product ion peaks by a single ion mobility spectrometry, and effectively separating sulfur-containing samples such as black powder and nitrogen-containing samples; the separation degree of air reagent ion peaks and sulfur product ion peaks is improved, and the detection sensitivity is improved, thereby improving the analysis and identification ability of ion mobility spectrometry for sulfur-containing samples such as black powder and nitrogen-containing samples; and the invention is easy to implement, and does not need to add any chloride additives to the migration gas and the carrier gas; compared with the traditional signal averaging method ion mobility spectrometry, the separation degree of air reagent ion peaks and sulfur product ion peaks is improved to above 2.0, and baseline separation is completely achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 is a structural diagram of a thermal desorption ion mobility spectrometer according to a fourth embodiment of the present invention;

[0029] Figure 2 It is the signal averaged ion mobility spectra of the air reagent ion peak and the sulfur product ion peak in the negative ion mode as a control;

[0030] Figure 3 is a Fourier deconvoluted ion mobility spectrum of an air reagent ion peak and a sulfur product ion peak in a negative ion mode in Example 1 of the present invention;

[0031] Figure 4 is the response curve and linear standard curve of disulfide in the embodiment of the present invention;

[0032] Figure 5 This is a Fourier deconvoluted ion mobility spectrum of sulfur-containing samples (black powder, firecrackers) detected by ion mobility spectrometry in negative mode in Example 3 of the present invention;

[0033] Figure 6 This is a Fourier deconvoluted ion mobility spectrum of the nitrogen-containing sample TNT detected by ion mobility spectrometry in negative mode in Example 3 of the present invention; DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0035] The present invention provides a method and device for rapid and sensitive detection of trace sulfur-containing samples, which uses Fourier deconvolution multiplexed ion mobility spectrometry technology to achieve direct separation of air reagent ion peaks (O2 − (H2O) n ) and the product ion peaks of sulfur-containing samples such as black powder, as well as an analytical method for effectively separating nitrogen-containing samples.

[0036] Figure 1-6 The experimental spectra given are for the purpose of illustrating the present invention. The experimental conditions are as follows: the temperature of the migration tube is maintained at 90°C, the temperature of the thermal desorber sample introduction unit is 200°C, and the gas flow rates of the migration gas and the carrier gas are 300 ml / min and 40 ml / min, respectively.

[0037] Embodiment 1

[0038] Figure 3 is the air reagent ion peak in negative ion mode ( Fourier deconvoluted ion mobility spectra of the product ion peak (PIP) of sulfur (5 ng, RIP) and sulfur (5 ng). The temperature of the migration tube was 90°C, the temperature of the thermal desorption sample introduction unit was 200°C, and the gas flow rates of the migration gas and carrier gas were 300 ml / min and 40 ml / min, respectively. It can be seen from the figure that the air reagent ion peak (RIP) and the sulfur product ion peak (PIP) are completely separated, the migration time of RIP is 5.18 ms, the migration time of PIP is 5.35 ms, the time interval between the two peaks is 0.17 ms, the separation degree between RIP and PIP is 1.67, achieving complete baseline separation, and the signal-to-noise ratio of PIP is 916.7.

[0039] Figure 2 is the air reagent ion peak in negative ion mode ( , RIP) and sulfur (5 ng) product ion peak (PIP) using traditional signal averaging method. The ion gate pulse width is 0.12 ms, the migration tube temperature is 90°C, the thermal desorption sample introduction unit temperature is 200°C, and the gas flow rates of the migration gas and carrier gas are 300 ml / min and 40 ml / min, respectively. It can be seen from the figure that RIP and PIP partially overlap, and the separation degree is only 0.71, indicating that the traditional signal averaging method has difficulty in separating the sulfur product ion peak; the signal-to-noise ratio of PIP is 171.1. Comparison Figure 3 and Figure 2It can be found that the present invention does not require any chloride additives and can achieve complete baseline separation of the air reagent ion peak (RIP) and the sulfur product ion peak (PIP), with a separation degree improved by 135.2%, a signal-to-noise ratio improved by 5.4 times, and high sensitivity and resolution.

[0040] Embodiment 2

[0041] Figure 4 The response curve and linear standard curve of sulfur are shown in Figure 2. The temperature of the migration tube is 90°C, the temperature of the thermal desorption sample introduction unit is 200°C, and the gas flow rates of the migration gas and carrier gas are 300 ml / min and 40 ml / min, respectively. It can be seen from the figure that the detection mass of sulfur is 0.1 5.0 ng, R 2 The detection limit is 0.994, and the detection signal intensity tends to saturate when the mass is further increased. According to the signal intensity corresponding to 0.1 ng, the detection limit calculated by 3 times the signal-to-noise ratio is 3 pg.

[0042] Embodiment 3

[0043] Figure 5 This is the Fourier deconvolution ion mobility spectrum of sulfur-containing samples (black powder, firecrackers) detected by ion mobility spectrometry in negative ion mode. It can be seen from the figure that the Fourier deconvolution ion mobility spectrometry technology can be used to detect trace black powder and firecrackers without any chloride additives. The migration time of its product ion peak (5.35 ms) is consistent with that of the sulfur product ion peak; therefore, it is reasonable to systematically study sulfur as an effective component for black powder detection in ion mobility spectrometry. Figure 6 This is the Fourier deconvolution ion mobility spectrum of the nitrogen-containing sample TNT detected by ion mobility spectrometry in negative ion mode. Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 It can be explained that the method of the present invention adopts a miniaturized migration tube and does not add any chloride additives to the migration gas and the carrier gas, and can effectively separate the RIP from the product ion peak (PIP) of black powder with high sensitivity, which is of great significance for the sensitive, accurate and rapid detection of explosives such as black powder by miniaturized / portable ion mobility spectrometer.

[0044] Embodiment 4

[0045] This embodiment provides a trace detection device for sulfur-containing samples, such as Figure 1As shown, it specifically includes: a thermal desorption sample introduction unit 1, an injection port 7, a gas outlet 9, an ion source 8, a reaction zone 10, an ion gate 11, a migration zone 13, a migration gas inlet 16, a detector, a multiplexed ion gate control unit 19, a migration tube high voltage control unit 12, a Fourier deconvolution ion mobility spectrometer control unit 17 and a display device 18. The detector includes a Faraday disk 14 and an amplifier 15; the Fourier deconvolution ion mobility spectrometer control unit 17 is connected to the migration tube high voltage control unit 12, the amplifier 15, the multiplexed ion gate control unit 19, and the display device 18 respectively.

[0046] The thermal desorption sample introduction unit 1 is provided with a carrier gas inlet 2, a carrier gas and sample gas outlet 3, a thermal desorption chamber 5, an exhaust port 4 and a silicone membrane 6; the exhaust port 4 is connected to an air pump; the reaction zone 10 is provided with an ion source 8, a gas outlet 9 and an injection port 7; an ion gate 11 is provided between the reaction zone 10 and the migration zone 13, and the ion gate 11 is connected to a multiplexed ion gate control unit 19; a Faraday disk 14 is provided on the other side of the migration zone 13, and is connected to an amplifier 15; a display device 18 is used to display the migration spectrum finally obtained.

[0047] The ion source 8 can be a corona discharge, high energy photoionization, nickel source, dielectric barrier discharge, secondary electrospray or ultraviolet lamp ionization source.

[0048] The ion gate 11 may be a Tyndall-Powell type or a Bradbury-Nielson type ion gate.

[0049] The thermal desorption sample introduction unit 1 is used to analyze the sample to be detected, and the carrier gas and sample gas outlet 3 is connected to the sample inlet 7.

[0050] The thermal desorption chamber 5 is provided with a sampling sheet; the sampling sheet may be glass fiber cloth, sampling paper, polytetrafluoroethylene sheet or metal grid.

[0051] The multiplexed ion gate control unit 19 can be a host computer that presets a control sequence pulse signal, or a SOC combined with an FPGA to generate the required control sequence pulse signal on site.

[0052] The drift tube high voltage control unit 12 can be a positive high voltage, a negative high voltage or a positive / negative polarity fast switching high voltage.

[0053] The ion mobility spectrometer operates at atmospheric pressure. The ionization source is radioactive 63 Ni source. The temperature of the migration tube is 90℃. The temperature of the thermal desorber sample introduction unit is 200℃. The migration gas and carrier gas are purified air. The gas flow rates of the migration gas and carrier gas are 300 ml / min and 40 ml / min respectively. The outer dimension of the migration tube is 2.0 The length of the reaction zone is 2.0 cm, the length of the migration zone is 7.23 cm, and the length of the reaction zone is 2.30 cm. A 0.1 mm thick stainless steel grid is set at the front end of the reaction zone, close to the first electrode. The ion gate is composed of two 0.1 mm thick stainless steel grids, with a 0.2 mm insulating ring between the two grids, and the insulating ring is made of polytetrafluoroethylene film. The ion gate control voltage is plus or minus 35 V. The amplifier amplification factor is 500 million times.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A trace detection method for sulfur-containing samples, characterized in that: include: The ion mobility spectrometer for detecting sulfur-containing samples adopts Fourier deconvolution multiplexing technology, and purified air is used as the migration gas and carrier gas, and the migration gas and carrier gas do not add any chloride additives. The sulfur-containing samples are black powder, gun ammunition or firecrackers, and nitrogen-containing samples can also be detected.

2. The method for detecting trace amounts of sulfur-containing samples according to claim 1, characterized in that: The Fourier deconvolution multiplexing technology refers to the steps of performing Fourier deconvolution on the gated modulated pulse signal of the multiplexed ion gate and the composite ion current signal collected by the detector to obtain an ion migration spectrum.

3. The trace detection method for a sulfur-containing sample according to claim 1, characterized in that: The purified air is air purified by using one or more of silica gel, activated carbon and molecular sieve as migration gas and carrier gas, and no chloride additive is added to change the air peak position.

4. The method for detecting trace amounts of sulfur-containing samples according to claim 1, wherein: The nitrogen-containing sample is TNT, ANFO, RDX or PETN.

5. A trace detection device for sulfur-containing samples using the method of claim 1, characterized in that: include: A multiplexed ion gate control unit, an ionization source, a migration tube, a migration tube high-voltage control unit, a thermal desorption sample introduction unit, an amplifier and a Fourier deconvolution ion mobility spectrometer control unit; the Fourier deconvolution ion mobility spectrometer control unit also includes a detection mode control unit.

6. The device according to claim 5, characterized in that The ionization source is corona discharge, high energy photoionization, nickel source, dielectric barrier discharge, secondary electrospray or ultraviolet lamp ionization source.

7. The device according to claim 5, characterized in that The multiplexed ion gate control unit comprises an input control end and an output high voltage end, the input control end is connected to the Fourier deconvolution ion mobility spectrometer control unit, and the output high voltage end is connected to the ion gate.

8. The device according to claim 5, characterized in that The detection mode control unit includes one or more of a positive ion mode, a negative ion mode or a positive / negative polarity fast switching mode.

9. The device according to claim 5, characterized in that The migration tube also includes an injection port, which is connected to the thermal desorption sample introduction unit.

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