CN103594327A - Ionic migration spectrometer and method for improving detection sensitivity of ionic migration spectrometer - Google Patents
Ionic migration spectrometer and method for improving detection sensitivity of ionic migration spectrometer Download PDFInfo
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Abstract
A method for improving detection sensitivity of an ionic migration spectrometer includes the steps that a sample is inserted into a sample inlet device of the ionic migration spectrometer; a spectral line collection operation is triggered through an optical coupler inductor; when the number of collected spectral lines reaches information amount needed when an explosive with high vapor pressure is accurately detected, an electromagnetic valve is controlled to be started, so that doping agents are added instantly into an ionization reaction area; when the number of the collected spectral lines reaches information amount needed when an explosive with low vapor pressure is accurately detected, the collection operation is stopped, and meanwhile the electromagnetic valve is shut off so that the doping agents are stopped from being added into the ionization reaction area; all the collected spectral lines are analyzed to obtain a detection result. Due to the fact that the time when the doping agents are added is controlled, the doping agents play a role in detection of the explosives with low vapor pressure, under the condition that the doping agents are not added, the explosive with high detection sensitivity can be analyzed when the content of the doping agents is low, detection effects of the spectrometer on different explosives are taken into consideration, and the best effect is achieved.
Description
The application is to be that July 31, application number in 2009 are 200910089161.1 and the dividing an application of the denomination of invention application for a patent for invention that is " ionic migration spectrometer and the method that improves its detection sensitivity " the applying date.
Technical field
The present invention relates to a kind of checkout equipment and detection method of explosive, relate in particular to a kind of ionic migration spectrometer of explosive detection and add opportunity to improve the method for this ionic migration spectrometer to explosive detection sensitivity by controlled doping agent.
Background technology
Instrument-the ionic migration spectrometer detecting based on Ion mobility spectrometry is a kind of Site Detection instrument of quick, sensitive, portable operation.This instrument can detect trace contraband, as the existence of explosive, drugs, chemical warfare agent etc., in fields such as safety check and military affairs, is widely applied at present.
The core component of ionic migration spectrometer is transference tube, and its carrier gas conventionally adopting is that ambient air is atmospheric air.Through different input modes, can make the measured matter molecule that collects with gaseous form along with air enters transference tube, ionization district at transference tube, first air molecule is ionized and forms reactant ion group, test substance molecule and reactant ion group interact and form new molecular ion group, i.e. sample product molecular ion group.When ion gate is opened, these molecular ion groups enter migration area and continue and move and advance under the effect of electric field under the effect of electric field.In migration area, the factor analysis such as the migration velocity of molecular ion group and its quality, electrically charged number, space structure, therefore it is different that different molecular ion groups arrives time of the detector that is positioned at migration area end, by detecting ion cluster, strike weak current and the corresponding ion time of advent thereof producing on detector, and it is mated with standard substance storehouse, just can judge the kind of material.
The ionization of the testing sample gas molecule carrying out in the ionization district of transference tube is secondary ionization process: it is more easily the ionization of ion source institute in sample vapor molecule that the concentration ratio of carrier gas and sample vapor causes carrier gas molecules, therefore first ionization process carries out air molecule, reaction of formation thing ion.Because the free path of ionization carrier gas molecules is far smaller than the physical dimension of reative cell, ionization carrier gas molecules and sample vapor intermolecular by frequent impact, thereby make ionic charge from ionization carrier gas molecules transfer to sample molecule.Transfer reaction between this electric charge determines by proton or the electron affinity of participating in the molecule of reaction, and electric charge can be from proton or the little molecular transfer of electron affinity above the large molecule of affinity.In the actual use of ionic migration spectrometer, conventionally by adding the mode of dopant to change molecular composition and the ionization mechanism of reactant, thereby change the chemical composition of the product ion generating, to improve detection sensitivity and the selectivity of instrument.Doping reagent molecule must possess lower than sample molecule (as explosive) but higher than the electron affinity of contained other component in carrier gas, therefore preferentially ionization generates stable ion, to avoid having in carrier gas compared with the chaff interference of low-affinity, participate in ionization reaction, electron affinity due to sample molecule is greater than reagent molecule simultaneously, and these ions generate with sample vapor molecular reaction then again can be for the sample molecule ion detecting.Adding of dopant also can make spectrogram peak position corresponding to product ion generating be moved, while making originally not add doping reagent, because peak position overlaps, impalpable quasi-molecular ions is separated, thereby realizes the identification to component to be measured under chaff interference existence.
At present existing a plurality of Patents, describe respectively the kind selection of dopant in ionic migration spectrometer or other similar analytical instrument and add mode.Early stage patent, as EP0135747, has been described in the detection of drugs and explosive sample, before sample injects, respectively acetone and carbon tetrachloride is added to carrier gas as dopant, the dimer ion of generation or hydration Cl
-ion, can stop the indefinite composition Cluster Phenomenon of water, makes it on ion spectrogram, form relatively-stationary narrow peak, position, can be used as the reference point of ECU (Electrical Control Unit) algorithm, makes instrument have better detection and Identification specificity.
Relevant patent documentation can be used for different types of dopant that ion mobility spectrometry is analyzed as WO2006123107, EP0509171, US5283199, US5234838, US5032721, DE19609582, DE10212110, WO2007085898 etc. have described, be applicable to various detection demands.As utilized the dopant containing two pentanones to improve Cucumber in gaseous sample as the recognition capability of nitrogen-containing compound in mammal expiratory air body; By controllable temperature osmos tube, a small amount of sulfur dioxide dopant is added to testing sample, can eliminate the weak acid gas components of electron affinity as the interference effect of Fuization Qing ﹑ titanium dioxide Liu ﹑ mefenamic acid, improve the selectivity of instrument; Equally a small amount of substituted phenol (as gaultherolin, 2-hydroxy acetophenone) and amine (as methylamine) are used as to dopant, can eliminate the interference effect of chlorine; Utilize and add the cluster ions that dopant dimethyl methyl phosphonate (DMMP) can obviously change with component ammonia generation transit time to be measured generation, thereby can from the spectrogram of mist, identify easily; In sample, add aromatic compound (benzene, toluene, dimethylbenzene) as dopant, have be equal to or less than VUV ray light quantum energy and higher than the ionization potential of sample molecule, within the scope of the ionization of VUV radioactivity, can be used for detecting trace materials in air, the material only with weak proton affinity even likely detected, and can improve the detection sensitivity of electronegativity material; By introduce ammoniacal liquor in analytical gas, reactant ion peak and formaldehyde peak are separated, then PARA FORMALDEHYDE PRILLS(91,95) carry out quantitative analysis; Utilize amide-type ionization dopant to detect peroxide explosive etc.
In adding in mode of dopant, the patent relating to is as PCT patent WO2006129101 and WO2004102611, instrument described in the former adopts at least two storage tanks so that multiple different dopant to be provided, the ionization chamber of storage tank and spectrometer is connected, add entrance and be located at the side that permselectivity membrane faces injection port, make sample gas before ionization and dopant contact, in migration tube, circulation gas circuit is isolated with the gas circuit of adulterating; The system that the latter describes comprises the molecular sieve that has added dopant, can add continuously the first dopant, system also comprises the other storage tank that different dopant is housed, and by switch, is arranged to selectivity in air and is added other the different dopant except the first dopant.In addition, the device that US Patent No. 6495824 relates to comprises a plurality of storage tanks that multiple doping reagent is housed, and according to the variation of detection signal, the difference reagent that adulterates is added in carrier gas air-flow selectively, and example reaction generates and has adding and product of different mobilities.Can set up an information bank, the known response information that comprises determinand and different dopant, by the observed result of the relatively multiple doping reagent of sample particular combination and the data in information bank are compared, can determine in sample, whether really to contain test substance.Patent WO2007082941 injects determinand by the normal pressure ionization interface of instrument entrance, additive is added in vaporific gas simultaneously.US2002088936 combines doping source of the gas and dry cleansing device.The closed container of US5491337 before being placed in instrument sample air entrance, the dopant of low concentration is mixed mutually with carrier gas, and sample gas is together introduced ionization chamber.EP1672363 mixes mutually with impurity gas before sample gas enters instrument, or impurity gas is added in migration gas to the interference problem while eliminating by a large amount of inert gas specimen of ionic migration spectrometer analysis.
In these prior aries, for the dopant of explosive detection, mostly be halogenated hydrocarbon, as chloralkane.Container for splendid attire dopant need have the flow rate control devices such as temperature and pellicle, to produce the sample introduction gas with constant flow rate that contains specific dopant content.Device can comprise the container of two or more splendid attire variety classes dopants, by electromagnetically operated valve etc., the selectivity of controlling inhomogeneity dopant being set adds, to improve the ability of instrument correct identification determinand when chaff interference exists, or for the detection demand of different determinands.
In the practical operations such as safety check, find, dopant to some important explosives as hexogen RDX, detection sensitivity and the selectivity of pacifying very much PETN etc. have good improvement effect, but adding not of dopant is all improved effect to the detection performance of all explosives, to some explosive, as DNT, black powder etc., under the condition existing in no dopant, can realize higher detection sensitivity, dopant adds as chlorohydrocarbon molecule, can make on the contrary sensitivity greatly reduce.Therefore, if according to the method that temperature control and osmos tube provide the dopant dose with constant density of passing through of common employing, be difficult to realize the optimum detection performance index to above-mentioned different explosives, and the preparation of temperature control and permeability apparatus and replacing simultaneously, increased complexity and the cost of instrument.
Summary of the invention
Shortcoming for above-mentioned prior art, the invention provides a kind of ionic migration spectrometer of explosive detection and by the adding opportunity of controlled doping agent, to realize this ionic migration spectrometer of front and back adding at dopant, different explosives is all there is to the method for high detection sensitivity.
Ionic migration spectrometer of the present invention, mainly comprises: sampling device, migration tube, air-channel system and circuit control system.Described migration tube is divided into ionization reaction zone and gas migration area by ion gate, and described air-channel system comprises: dry gas circuit, migration gas circuit, doping gas circuit and unloaded gas circuit, wherein,
The air of described dry gas circuit for providing dry decontamination to cross to migration gas circuit, doping gas circuit, unloaded gas circuit respectively;
Described migration gas circuit is for importing air that above-mentioned dry decontamination crosses as migration air-flow from instrument rear end to gas transfer district;
Described doping gas circuit is for appropriate dopant steam is provided, and the air of crossing according to the dry decontamination of the dry gas circuit of external control instruction connection, and dopant steam is imported to ionization reaction zone;
Described unloaded gas circuit is for importing to ionization reaction zone the air that above-mentioned dry decontamination is crossed.
In ionic migration spectrometer of the present invention, described dry gas circuit comprises from the aspiration pump of extraneous extracting air with for the device for drying and filtering of this outside air of dry decontamination.
In ionic migration spectrometer of the present invention, described doping gas circuit comprises and is dried the entrance electromagnetically operated valve that gas circuit is connected and the outlet electromagnetically operated valve being connected with ionization reaction zone, between described entrance electromagnetically operated valve and outlet electromagnetically operated valve, be provided with the container of splendid attire dopant, described entrance electromagnetically operated valve is a two-position three-way valve, according to external control instruction, selects to make dry gas circuit and doping gas circuit are connected or dry gas circuit and unloaded gas circuit are connected;
When the content of external control instruction is when opening, described outlet electromagnetically operated valve is opened, and entrance electromagnetically operated valve is communicated with dry gas circuit and doping gas circuit;
When the content of external control instruction is when closing, described outlet closed electromagnetic valve, entrance electromagnetically operated valve is communicated with dry gas circuit and unloaded gas circuit.
The present invention also provides a kind of method that improves ionic migration spectrometer detection sensitivity, comprises the steps:
Step 1, inserts testing sample the sampling device of ionic migration spectrometer;
Step 2, by being arranged on the optocoupler inductor at sampling device place, trigger the spectral line acquisition operations of ionic migration spectrometer, the spectral line that this collects shows the real time information of ionic bombardment to the weak current of the sign ionic strength producing on detector and ion time of advent;
Step 3, when the spectral line number collecting reaches when the required amount of information of explosive that accurate detection vapour pressure is higher can be provided, by controlling opening state instantaneous dopant that adds in ionization reaction zone of electromagnetically operated valve;
Step 4, when the spectral line number collecting reaches when the required amount of information of explosive that accurate detection vapour pressure is lower can be provided, stops acquisition operations, stops adding dopant in ionization reaction zone by controlling the opening state of electromagnetically operated valve simultaneously;
Step 5, carries out Algorithm Analysis to the above-mentioned whole spectral lines that collect, and obtains testing result.
In the step 2 of the method for raising ionic migration spectrometer detection sensitivity of the present invention, the insertion time of described optocoupler inductor perception sample, and immediately trigger the spectral line acquisition operations of ionic migration spectrometer.
In the step 2 of the method for raising ionic migration spectrometer detection sensitivity of the present invention, described spectral line information is for representing the scanning mean value of the real time data of weak current that detector detects and ion time of advent.
In the step 2 of the method for raising ionic migration spectrometer detection sensitivity of the present invention, described low current signal is to be detected by the detector that is positioned at migration tube end, the current inductor that the molecular ion group that this low current signal is formed by measured matter molecule clashes on detector under electric field action after migration tube separation produces, and can characterize the intensity that molecular ion is rolled into a ball, described electric field is formed by ring electrode sheet.
In the step 3 of the method for raising ionic migration spectrometer detection sensitivity of the present invention, described dopant is the solid dopants that volatile quantity is little.In the present invention, the preferred version of described dopant is carbon trichloride.
In the step 3 of the method for raising ionic migration spectrometer detection sensitivity of the present invention, add the gas circuit of dopant to comprise the polytetrafluoro container of accommodating dopant, these container two ends are provided with electromagnetically operated valve.
In the method for raising ionic migration spectrometer detection sensitivity of the present invention, also comprise migration gas circuit, this migration gas circuit with described in add the gas circuit of dopant to be arranged in parallel, when the content of the external control instruction receiving is when closing, the electromagnetically operated valve that the polytetrafluoro container two ends of accommodating dopant arrange is communicated with dry gas circuit and unloaded gas circuit, make the air after drying gas circuit dry decontamination partly be used as the migration gas adding from migration tube tail end, part directly enters the ionization reaction zone of migration tube; When the content of the external control instruction receiving is when opening, the electromagnetically operated valve that the polytetrafluoro container two ends of accommodating dopant arrange is communicated with dry gas circuit and doping gas circuit, make the air after part drying gas circuit dry decontamination pass through doping gas circuit, carry the ionization reaction zone that dopant enters migration tube.
In the method for raising ionic migration spectrometer detection sensitivity of the present invention, before the electromagnetically operated valve that the agent of each analysis unlatching controlled doping adds, the spectral line number of required collection is for setting in advance.
In the step 5 of the method for raising ionic migration spectrometer detection sensitivity of the present invention, ion current intensity peak and corresponding ion thereof that spectral line is shown mate with standard substance storehouse the time of advent, to determine measured matter kind.
The present invention only uses a kind of dopant, by adding opportunity of controlled doping agent, the impact on its actual detection performance according to the difference of the gasification rate of different explosives and dopant, guarantee that those explosives that detection sensitivity is higher in the situation that not adding dopant can analyze when dopant content is lower, simultaneously, under the state that explosive that those detection sensitivities in the situation that adding dopant are higher can be heightened at dopant dose, obtain detection signal, thereby take into account the sensitivity requirement to different explosives in actual detection, and can improve the selectivity of instrument, reduce rate of false alarm.
Accompanying drawing explanation
Fig. 1 is the structural representation of the ionic migration spectrometer of described method application of the present invention;
Fig. 2 is the flow chart of the method for raising ionic migration spectrometer detection sensitivity of the present invention;
Fig. 3 is in embodiments of the invention, the Spectral Overlapping schematic diagram automatically gathering after 10ngDNT sample introduction in the situation that not adding dopant;
Fig. 4 is in embodiments of the invention, the Spectral Overlapping schematic diagram automatically gathering after 50ngRDX sample introduction in the situation that not adding dopant;
Fig. 5 A, 5B are in embodiments of the invention, add the 50ngRDX testing result contrast of doping front and back under similarity condition: wherein, Fig. 5 A is for adding the front spectrogram of doping, and Fig. 5 B is for adding the rear spectrogram of doping;
Fig. 6 A, 6B are in embodiments of the invention, add the 10ngDNT testing result contrast of doping front and back under similarity condition: wherein, Fig. 6 A is for adding the front spectrogram of doping, and Fig. 6 A is for adding the rear spectrogram of doping;
Fig. 7 A, 7B are in embodiments of the invention, adding of controlled doping agent detects the improvement effect schematic diagram of performance opportunity to explosive (50ngRDX): wherein, Fig. 7 A is 10 Spectral Overlapping schematic diagrames after sample introduction while not adding dopant, and Fig. 7 B is by the chart adding schematic diagram after the 3rd the instantaneous unlatching doping of spectral line valve sample introduction.
Fig. 8 A, 8B are in embodiments of the invention, adding of controlled doping agent detects the improvement effect schematic diagram of performance opportunity to explosive (10ngDNT and 50ngRDX): wherein, 10 Spectral Overlapping schematic diagrames when Fig. 8 A adulterates for not adding after 10ngDNT sample introduction, Fig. 8 B is by the chart adding schematic diagram after the 3rd the instantaneous unlatching doping valve 10ngDNT of spectral line and 50ngRDX biased sample sample introduction.
Embodiment
By reference to the accompanying drawings, explain below and improve the method for ionic migration spectrometer to explosive detection sensitivity, and the concrete structure of realizing the equipment of this method.
The present invention is based on such understanding, by adding opportunity of controlled doping agent, improve the detection sensitivity of ionic migration spectrometer to variety classes explosive.When dopant being joined to ionization region, electric charge will being at war with property distribute between dopant molecule and air molecule, preferentially ionization generates stable ion, generating with sample vapor molecular reaction can be for the sample molecule ion detecting again, to avoid having in carrier gas compared with the chaff interference of low-affinity, participate in ionization reaction, thereby improve detection sensitivity and the selectivity of instrument.
Adding not of dopant all has improvement effect to all explosive detection effects, and in fact some explosive can have better detection sensitivity when no dopant exists.Therefore, by adding the setting of the trigger timing of dopant, can control the joining day of dopant in test process, this can realize and take into account the detection effect of instrument to different explosives, thereby best performance index are provided.
As shown in Figure 1, according to raising ionic migration spectrometer of the present invention to the method for explosive detection sensitivity in, applied ionic migration spectrometer 1 comprises sampling device 2, migration tube 3 and the air-channel system being comprised of dry gas circuit 14, migration gas circuit 15, doping gas circuit 16.
The core component that described migration tube 3 is ionic migration spectrometer, it is separated into ionization reaction zone 4 and gas migration area 6 by ion gate 5.In gas transfer district 6, by the ring electrode sheet 7 arranging, impose voltage equally distributed electric field is provided, the measured matter molecule gathering with gaseous form by sampling device 2 along with air enters migration tube 3, ionization reaction zone 4 at migration tube 3, air molecule is ionized and forms ion cluster, and explosive molecule and these ion clusters interact and form new molecular ion group.When ion gate 5 is opened, these molecular ion groups move and advance under the effect of ring electrode sheet 7 formed electric fields, and arrive the detector 8 of gas transfer district 6 ends.The time that arrives detector 8 due to different molecular ion groups is different, therefore can strike weak current and the corresponding time of advent thereof producing on detector by detection molecules ion cluster, and it is mated with standard substance storehouse, so just can determine the kind of measured matter.
Now described air-channel system is described further, to explain in more detail the operation principle of present device.Shown in Fig. 1, the dry gas circuit shown in mark 14 comprises aspiration pump 9 and device for drying and filtering 10.The air being extracted from external environment by aspiration pump 9, after device for drying and filtering 10 purge dryings, a part enters the migration gas circuit shown in mark 15, as migration air-flow, from the rear end of instrument (migration tube 3), enter gas transfer district 6, a part of by entering the ionization reaction zone 4 of instrument front portion with migration gas circuit 15 other gas circuit in parallel, this another gas circuit is formed in parallel by the unloaded gas circuit (not illustrating with mark in figure) that the doping gas circuit 16 of dopant adding apparatus is set and dopant adding apparatus is not set.The on off state of placing electromagnetically operated valve 11 that polytetrafluoro container 12 two ends of dopant arrange and 13 in gas circuit 16 by doping can be realized the operation that adds of controlled doping agent.Wherein, the entrance electromagnetically operated valve 11 of described doping gas circuit is for example two-position three-way valve, be connected with the outlet of dry gas circuit 14 that comprises device for drying and filtering 10 and the entrance of unloaded gas circuit respectively, it is communicated with dry gas circuit 14 and doping gas circuit 15 when the first state, and it is communicated with dry gas circuit 14 and unloaded gas circuit when the second state.The outlet electromagnetically operated valve 13 of described doping gas circuit is connected with the gas access of ionization reaction zone 4.
When the external control instruction receiving when electromagnetically operated valve 11 and 13 is the first state, shown placement the two ends electromagnetically operated valve 11 of polytetrafluoro container 12 and 13 status of dopant dry gas circuit 14 and unloaded gas circuit are communicated with, thereby the part of the air after drying gas circuit dry decontamination is as the migration gas adding from migration tube 3 tail ends, and remaining part directly enters the ionization reaction zone 4 of migration tube through unloaded gas circuit simultaneously.When the content of the external control instruction receiving when electromagnetically operated valve 11,13 is the second state, electromagnetically operated valve 11 and 13 status are communicated with dry gas circuit 14 and doping gas circuit 16, thereby make the air after part drying gas circuit dry decontamination pass through doping gas circuit 16, carry the ionization reaction zone 4 that dopant enters migration tube 3 simultaneously.
Described doping gas circuit 16 can provide appropriate dopant steam.According to external control instruction, it is communicated with dry gas circuit 14, and the air that drying purified, imports to ionization reaction zone 4 by dopant steam.In the present invention, for example, using carbon trichloride (solid) as a kind of exemplary dopant.In embodiments of the invention, the carbon trichloride that takes a morsel packs in clean polytetrafluoro container 12, in container two end cap, pore is set, again this container is placed in to stainless steel storage tank, its two ends are connected with pipeline, and by electromagnetically operated valve 11,13, the doping gas circuit 16 shown in having formed.
The described unloaded gas circuit being arranged in parallel with doping gas circuit 16 is single pipeline, any extra device is not set especially, its one end is connected with dry gas circuit 14 outlets that comprise device for drying and filtering 10 by entrance electromagnetically operated valve 11, and the other end is connected with the gas access of ionization reaction zone 4.
According to above description, the Income Air Status of the gas access of ionization reaction zone 4 comprises two kinds of situations: the one,, outlet electromagnetically operated valve 13 in doping gas circuit 16 cuts out, and when entrance electromagnetically operated valve 11 has been communicated with dry gas circuit 14 and unloaded gas circuit, the gas entering is the dry air after purifying; Another kind is, when the outlet electromagnetically operated valve 13 of doping gas circuit 16 opens that entrance electromagnetically operated valve 11 has been communicated with dry gas circuit 14 and doping gas circuit simultaneously 16 o'clock, under the air of dopant steam after drying purifies carries, enters ionization reaction zone 4.
On basis described above, understandable for technicians, according to ionic migration spectrometer of the present invention, also comprise control circuit, it can be used for realizing the control to electromagnetically operated valve 11 and 13, although do not illustrate in the drawings.In addition, go back the real-time information collection operation that control circuit is also controlled detector.And also comprise and analytical equipment contrast for data analysis with according to the standard substance storehouse prestoring.This control circuit and analytical equipment can separate, and can carry out signal communicating between now, also can integrate alternatively.And, can be realized by hardware, or can under the operation of programming software, be realized by general processor, and can be realized by combination of hardware software.
Below with reference to Fig. 2 and in conjunction with Fig. 1, illustrate further and improve the method for ionic migration spectrometer to explosive detection sensitivity.Particularly, the method comprises following step:
In this step, measured matter imports migration tube with gaseous molecular form after the sampling device of ionic migration spectrometer passes through gasification (volatilization).
In this step, air molecule is ionized and forms reactant ion group in ionization reaction zone, and tested explosive molecule interacts and forms new product with these ion clusters: molecular ion group.
When ion gate 5 is opened, under the effect of the electric field that these molecular ion groups form at ring electrode sheet 7, enter migration area, and continue to move and advance under the effect of electric field, finally arrive detector 8.
It should be noted that, due to factor analysis such as the migration velocity in molecular ion Tuan gas transfer district and its quality, electrically charged number, space structures, therefore, the time that different molecular ion groups arrives detector is different, that is to say, detector can detect the time dependent information that can survey peak shape that shows as, and represents the ion current intensity of the measured matter that priority arrives at, and it obtain for spectral line or the spectrogram analyzed after data processing.
Specifically, the spectrogram collection of detector and analytic process can start by the signal of the optocoupler inductor in sampling device setting.Optocoupler inductor, when sample is inserted into sampling device, produces electronic signal by the variation of light path, thus when sample is inserted into sampling device the instant spectral line acquisition operations that triggers ionic migration spectrometer.The spectral line collecting is the weak current of sign ionic strength and the real time information of ion time of advent that shows self-detector.Conventionally, the actual spectral line information of choosing means the scanning mean value of the real time data of weak current that detector detects and ion time of advent.Described low current signal is detected by the detector that is positioned at migration tube end, this low current signal is that the current inductor that the molecular ion group that formed by measured matter molecule clashes on detector under electric field action after migration tube separation produces, and can characterize the intensity of molecular ion group.Described electric field is formed by ring electrode sheet.
Test substance needs the regular hour in the gasification of sampling device, and the gasification rate of variety classes explosive is different, thereby (as 10) could obtain enough amount of information existing of various explosive compositions to be detected need to collect the spectral line of some time.
Some explosive is as higher in component saturated vapour pressures to be measured such as DNT, black powders, fast at air inlet gasification rate, goes out peak speed also fast; And some explosive is as lower in saturated vapour pressures such as RDX, PETN, slow at air inlet gasification rate, corresponding to go out peak speed also slow.As shown in Figures 3 and 4, demonstrate respectively in the situation that not adding dopant, the spectral line picture group of continuous acquisition during the lower explosive RDX of the higher explosive DNT of test saturated vapour pressure and saturated vapour pressure, this explosive that can reflect that vapour pressure is different goes out the difference of peak speed.Fig. 3 is 8 spectral lines that collect after 10ngDNT sample introduction, and wherein, material property peak occurs at second spectral line, at the 3rd spectral line, reaches peak-peak.Therefore, at instrument, start after spectral line acquisition operations, can from the spectral line of real-time change, reflect very soon component to be measured corresponding go out peak information, the initial some spectral lines (as first three) that gather of instrument can comprise the amount of information of enough analyses, whether prove the existence of this type of explosive.Fig. 4 is 10 spectral lines that collect after 50ngRDX sample introduction, and wherein, material property peak appears at the 4th spectral line, at the 7th spectral line, just reaches peak-peak.Therefore, at instrument, start after spectral line acquisition operations, by the spectral line of observation real-time change, need certain hour just can reflect component to be measured corresponding go out peak information, some spectral lines that instrument collects below (as 7 subsequently) just comprise the existence of this type of explosive whether information that proves.
Spectrogram or spectral line while adding dopant front and back instrument, under similarity condition, the sample characteristic peak collecting in same amount explosive sample test process is reached to peak by contrast, observable goes out the impact of dopant on different explosive detection performances.The result detecting according to reality, although dopant to some important explosives as hexogen RDX, detection sensitivity and the selectivity of pacifying very much PETN etc. have good improvement effect, but some explosive detection sensitivity in the situation that no dopant exists is higher, as DNT, black powder etc., dopant adds as chlorohydrocarbon molecule, can make on the contrary the detection sensitivity of sample greatly reduce.As shown in Fig. 5 A, 5B and Fig. 6 A, 6B, demonstrate respectively in the situation that not adding dopant (Fig. 5 A, 6A) and adding dopant (Fig. 5 B, 6B) the spectrogram contrast when sample characteristic peak gathering when test explosive RDX and DNT reaches peak.In Fig. 5 A, 5B, the test result of 50ngRDX shows, dopant to add the detection sensitivity of sample and selectivity be that sample characteristic peak height and peak shape all improve significantly; And the test result of 10ngDNT shows in Fig. 6 A, 6B, the adding of dopant making sample detection sensitivity is that sample characteristic peak height significantly reduces.Therefore, if adopt prior art, add all the time the dopant of equivalent in test process, in fact this cannot realize different explosives are all obtained to best detection effect.
Considered that different explosives go out the difference of peak speed, the present inventor recognizes: the explosive that detection sensitivity is higher in the situation that no dopant exists is as DNT, the component to be measured such as black powder only needs former spectral lines can obtain the amount of information of enough analyses, in order to detect determinand, whether exist, and the explosive that detection sensitivity is higher in the situation that adding dopant is as RDX, PETN etc., due to slow at sampling device gasification rate, until collect the maximum fault information that some spectral lines below could obtain sample, with whether existing of this type of explosive of valid certificates.Therefore, can, by the adding opportunity of controlled doping agent, realize the different requirements of different explosives to dopant dose.
In the present invention, when startup spectral line acquisition operations under the impelling of photosensor signal for example initially, the state of the outlet electromagnetically operated valve of doping gas circuit in closing, and by entrance electromagnetically operated valve, dry gas circuit and unloaded gas circuit being communicated, this can guarantee that those explosives that detection sensitivity is higher in the situation that not adding dopant can not carry out spectrum analysis when very low containing dopant or content; And can provide accurate analysis DNT, black powder etc. containing the higher required amount of information of explosive composition of vapour pressure when the spectral line number collecting reaches, after three spectral lines, change the electromagnetically operated valve state of doping gas circuit, the outlet electromagnetically operated valve of doping gas circuit is opened, and by entrance electromagnetically operated valve, dry gas circuit and doping gas circuit are communicated, thereby dopant steam is imported to ionization reaction zone.Because the explosive gasification rate that detection sensitivity in the situation that adding dopant is higher is slow, therefore, under the state that can heighten in dopant dosage, obtain these detection signals, taken into account the sensitivity testing requirement to different explosives in actual testing process.
So, in this step, when the spectral line number collecting reaches, can provide accurate analysis if DNT, black powder etc. are containing the higher required amount of information of explosive composition of vapour pressure, while being three as spectral line number, unlatching that can be by controlling electromagnetically operated valve is with the instantaneous dopant that adds in ionization reaction zone.Concrete, change the agent of electromagnetically operated valve state controlled doping at every turn and add the spectral line number of front required collection to be arranged in advance by the built-in software systems of instrument, also can modify according to condition.As shown in Fig. 7 B, when detecting 50ngRDX, when appearring in explosive DNT that vapour pressure is higher, spectral line corresponding to maximum characteristic peaks (i.e. the 3rd spectral line) add immediately dopant collecting.Can find out, due to hysteresis effect, at the 6th spectral line, there is obvious dopant characteristic peak, and, by contrasting with the spectral line of Fig. 7 A, can find adding of dopant peak height and the peak shape of the characteristic peak of the lower explosive RDX of vapour pressure all to be improved significantly, significantly improve detection sensitivity and the selectivity of sample.And, as shown in Figure 8 B, when detecting simultaneous 10ngDNT and 50ngRDX sample, equally at the 3rd instantaneous dopant that adds of spectral line, show with Fig. 8 A comparing result: the dopant adding, when the peak shape of RDX characteristic peak and peak height tool are had clear improvement, does not have influence on peak shape and the peak height of characteristic peak that goes out the DNT at peak at former spectral lines, visible, by adding opportunity of controlled doping agent, can take into account the sensitivity of ionic migration spectrometer to different explosive detection.
Described dopant is generally the solid dopants that volatile quantity is little.In the present invention, the preferred version of described dopant is carbon trichloride solid.The described gas circuit of dopant that adds comprises the polytetrafluoro container of accommodating dopant, and at these container two ends, is provided with the electromagnetically operated valve of controllable operation state.
In the present invention, also can comprise migration gas circuit, this migration gas circuit with described in add the gas circuit of dopant to be arranged in parallel, by external command, control the switch connected state of electromagnetically operated valve, make the air after drying gas circuit dry decontamination partly be used as the migration gas adding from migration tube tail end, remainder is directly entered the ionization reaction zone of migration tube by unloaded gas circuit, or by doping gas circuit, carry the ionization reaction zone that dopant enters migration tube.
In this step, when reaching, the spectral line number gathering can provide accurate analysis to comprise containing the lower required amount of information of various explosives of vapour pressure, for example, when spectral line number is 10, automatically stop acquisition operations, close doping gas circuit outlet electromagnetically operated valve simultaneously and be communicated with dry gas circuit and unloaded gas circuit by entrance electromagnetically operated valve, stopping adding dopant in ionization reaction zone.The above-mentioned corresponding spectral line number of acquisition operations that stops can being set in advance by instrument embedded software system.
In the present invention, the spectral line collecting comprises the real time information of faint pulse current that detector detects and corresponding ion time of advent thereof, and it is mated with standard substance storehouse, can determine the kind of measured matter.
Complete after one-time detection, dopant gas circuit need to be closed, close the outlet electromagnetically operated valve of dopant gas circuit and be communicated with dry gas circuit and unloaded gas circuit by entrance electromagnetically operated valve, like this, ionic migration spectrometer can substantially return to doping after finishing spectral line collection in 20 seconds very low or approach undoped state, ready for detect next time.
In the detection standby condition of above-mentioned judgement ionic migration spectrometer, can by doping ion pair is set, to answer peak height and carrier gas molecules ion be that the ratio of the corresponding peak height of reactant ion judges.If instrument adopts gas sampling pattern, need to wait for that this ratio drops to certain numerical value and just can test below, can extend analysis time although it is so, but the benefit of bringing in raising with respect to sensitivity, or of great practical value.And in actual anti-explosion safety inspection operation, adopting solid sampling pattern more, sampling process also needs the regular hour, can reduce to wait for the impact of dopant dose level recovery on analysis time.
Raising ionic migration spectrometer of the present invention is in the method for explosive detection sensitivity, only use a kind of dopant, by the joining day of controlled doping agent, the impact on its actual detection performance according to the difference of the gasification rate of different explosives and dopant, guarantee that those explosives that detection sensitivity is higher in the situation that not adding dopant can analyze when dopant content is lower, simultaneously, under the state that explosive that those detection sensitivities in the situation that adding dopant are higher can be heightened at dopant dose, obtain detection signal, thereby take into account the sensitivity requirement to different explosives in actual detection, and can improve the selectivity of instrument, reduce rate of false alarm.
It is emphasized that " comprise/comprise " as used in this specification, only for listing in detail the existence of described parts, step or element, also do not exist or be attached with other one or more parts, integral body, step, element or their combination but do not get rid of.
For one of ordinary skill in the art, various aspects of the present invention as mentioned above, obviously multi-form software, firmware and the hardware in available embodiment shown in the drawings is implemented.For implementing to meet actual software code and the concrete control hardware that the various piece of the principle of the invention adopts, the present invention is not caused to restriction.Therefore, to the description of the operation of the present invention part and performance not with reference to concrete software code.Be understood that any one of ordinary skill in the art can be described and design for implementing software and the control hardware of various piece of the present invention according to the present invention.
Claims (13)
1. improve the detection method that ionic migration spectrometer detects trace explosive performance, described method comprises:
Step 1, inserts testing sample the sampling device of ionic migration spectrometer;
Step 2, triggers the spectral line acquisition operations of ionic migration spectrometer by being arranged on the inductor at sampling device place, the spectral line that this collects shows the real time information of ionic bombardment to the weak current of the sign ionic strength producing on detector and ion time of advent;
Step 3, when the spectral line number collecting reaches when the required amount of information of explosive that accurate detection vapour pressure is higher can be provided, by controlling opening state instantaneous dopant that adds in ionization reaction zone of electromagnetically operated valve;
Step 4, when the spectral line number collecting reaches when the required amount of information of explosive that accurate detection vapour pressure is lower can be provided, stops acquisition operations, and the switch by controlling described electromagnetically operated valve is to stop adding dopant in ionization reaction zone simultaneously;
Step 5, analyzes the above-mentioned whole spectral lines that collect according to certain algorithm, thus the testing result of obtaining; And
Complete above-mentioned steps one after five, closing described dopant gas circuit.
2. the method for claim 1, is characterized in that, in described step 2, and the insertion time of described inductor perception sample, and immediately trigger the spectral line acquisition operations of ionic migration spectrometer.
3. the method for claim 1, is characterized in that, in described step 2, described spectral line information is the scanning mean value of the real time data of the weak current that characterizes detector and detect and ion time of advent.
4. the method for claim 1, it is characterized in that, in described step 2, described low current signal is to be detected by the detector that is positioned at migration tube end, the current inductor that the molecular ion group that this low current signal is formed by measured matter molecule clashes on detector under electric field action after migration tube separation produces, and can characterize the intensity that molecular ion is rolled into a ball, described electric field is formed by the ring electrode sheet that is positioned at migration tube.
5. the method for claim 1, is characterized in that, in described step 3, described dopant is the solid dopants that volatile quantity is little.
6. method as claimed in claim 5, is characterized in that, described dopant is carbon trichloride.
7. the method for claim 1, is characterized in that, in described step 3, adds the doping gas circuit of dopant to comprise the polytetrafluoro container of placing dopant, and its two ends are provided with controlled electromagnetically operated valve.
8. method as claimed in claim 7, is characterized in that, the ionic migration spectrometer using includes migration gas circuit, this migration gas circuit with described in add the doping gas circuit of dopant in parallel;
When described electromagnetically operated valve is the first state according to control signal, be communicated with dry gas circuit and doping gas circuit, wherein the part of the air after drying gas circuit dry decontamination is as the migration gas adding from migration tube tail end, simultaneously other part is passed through doping gas circuit, and carries the ionization reaction zone that dopant steam enters migration tube; When described electromagnetically operated valve is the second state according to control signal, be communicated with dry gas circuit and unloaded gas circuit, an air part after drying gas circuit dry decontamination, as the migration gas adding from migration tube tail end, partly directly enters the ionization reaction zone of migration tube simultaneously in addition.
9. the method for claim 1, is characterized in that, described in make the signal of electromagnetically operated valve in the first state the algorithm based on predetermined provide according to the signal of telecommunication of detector collection by control device.
10. the method for claim 1, is characterized in that, in described step 5, the shown ion current intensity peak of spectral line and corresponding ion thereof is mated to determine to the kind of detected material the time of advent with standard substance storehouse.
11. the method for claim 1, is characterized in that, in described step 3 and step 4, described enough information can collect enough spectral lines by detector and represent.
12. methods as claimed in claim 11, is characterized in that, the described enough spectral lines in step 3 are 3 spectral lines; Described enough spectral lines in step 4 are 10.
13. the method for claim 1, is characterized in that, answer the ratio of the corresponding peak height of peak height and reactant ion to judge the detection standby condition of ionic migration spectrometer by doping ion pair is set.
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