1、Designation: E 2520 07Standard Practice forVerifying Minimum Acceptable Performance of TraceExplosive Detectors1This standard is issued under the fixed designation E 2520; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is primarily intended to assist first re-sponders and security screeners in verifying the minimumaccep
3、table performance of detectors used to identify traces ofhigh explosives such as cyclotrimethylene trinitramine (RDX),pentaerythritol tetranitrate (PETN), and trinitrotoluene (TNT).These explosive detectors may be based on, but are not limitedto, ion mobility spectrometry (IMS).1.2 This practice is
4、used to evaluate the detector response toevaporated residues of low-concentration solutions of explo-sive compounds placed on test swipes. The solutions used forthis evaluation are prepared in a suitable organic solvent andcontain a single high explosive.1.3 This practice does not address or use sam
5、pling proce-dures common to the use of trace explosive detectors. It onlytests the response of the detector once a test swipe has beensuccessfully introduced into the explosive detector.1.4 This practice does not evaluate the effect of contami-nants or interferences that may be encountered in sampli
6、ng fortrace explosives in the field.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the use
7、r of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 blank solution, nsemivolatile solvent that does notcontain trace explosives to which
8、 the detector is sensitive.2.1.2 calibration, nact of providing the detector with aknown substance so that it may be adjusted to identifyexplosive compounds correctly.2.1.2.1 DiscussionManufacturers of explosives detectorsoften provide calibration swipes. In an ion mobility spectrom-etry (IMS) instr
9、ument, calibration allows the instrument toadjust the present values of the mobility (or drift) time of thecalibrant to the most current conditions. For explosives detec-tors based on mass spectrometry (MS), calibration is oftencalled tuning. Some IMS and MS explosives detectors mayhave built-in mat
10、erials and software to perform calibrationautomatically.2.1.3 instrument blank swipe, nunused swipe freshlyremoved from the container provided by the manufacturer.2.1.4 performance evaluation solution, ndilute solution ofa single explosive compound dissolved in a semivolatilesolvent.2.1.5 process bl
11、ank swipe, nsample swipe that has beendosed with the blank solution.2.1.6 sample swipe, npads that are made from varioustypes of materials, including fabric and paper, that are offeredby the equipment manufacturer to collect particle samples foruse in trace explosives detectors.2.1.6.1 DiscussionAls
12、o referred to as sample traps bysome manufacturers of trace explosives detectors.2.1.7 swipe support, nholder for the sample swipe thatsuspends the swipe preventing contact of the back side of thesampling area with any surface that might wick away drops ofsolution.2.1.8 test kit, nset of individual
13、solutions of the explo-sives and a blank solution to be used for the evaluation ofexplosives detector performance.2.1.8.1 DiscussionThe test kit may also include holdersused for supporting the sample swipes for solution application.2.1.9 test swipe, nsample swipe that has been dosed withone of the p
14、erformance evaluation solutions and dried.2.1.10 trace explosives detector, nan instrument designedto detect trace amounts (micrograms or less) of explosivecompounds.2.1.10.1 DiscussionIn the context of this standard prac-tice, a trace explosives detector will require the use of a swipesample collec
15、tor. These detectors are commonly based on, butnot limited to, ion mobility spectrometry.2.2 Acronyms:2.3 IMS, nion mobility spectrometry1This practice is under the jurisdiction of ASTM Committee E54 on HomelandSecurity Applications and is the direct responsibility of Subcommittee E54.01 onCBRNE Sen
16、sors as a demonstration by thevendor that the equipment is performing properly to a minimalstandard; or for a periodic verification of detector performanceafter purchase.3.2 This practice establishes the minimum performance thatis required for a detector to be considered effective in thedetection of
17、 trace explosives. An explosives detector is con-sidered to have “minimum acceptable performance” when ithas passed all of the evaluation tests without a failure.3.3 This practice uses three explosive compoundsRDX,PETN, and TNTthat are used to represent nitro-basedcompounds having a range of physica
18、l and chemical proper-ties. The concentrations of the solutions of explosive have beendetermined to be sufficient to provide a positive detector alarmsignal. In time, other compounds may be added or substitutedinto this practice as detection priorities dictate.3.4 This practice was developed using I
19、MS-based traceexplosives detectors, but this practice should also be applicableto any explosives detector designed to analyze trace levels ofhigh-explosive compounds collected on swipes.3.5 This practice does not include procedures to test forcompounds that may interfere with detector performance.3.
20、6 This practice does not test the minimum limit ofdetection or the dynamic range of the trace explosives detector.3.7 This practice does not test for compounds other thanhigh explosives.3.8 This practice only evaluates the response of the detectorto traces of pure explosive compounds.4. Performance
21、Evaluation Materials4.1 Test KitOne test kit contains:4.1.1 Test solutions of the specified concentrations of thehigh explosives that may be in plastic squeeze dropper bottlesin which each solution contains a single high explosive labeledwith the contents in isobutyl alcohol (2-methyl-1-propanol) or
22、another suitable solvent,4.1.2 One blank solution containing only alcohol, and4.1.3 Four swipe supports for holding the test and blankswipes for evaporation.4.2 Solution ConcentrationsSolution concentrations ofthe high explosives for the kit are: RDX concentration:0.14 mg/L providing 3 ng per drop;
23、TNT concentration:1.0 mg/L or 23 ng per drop; and PETN concentration: 1.7mg/L or 40 ng per drop. The volume of solution of explosivedelivered by a single drop is based on an average drop volumeof 23 Ldispensed by holding the bottle at approximately a 45angle.2A volumetric pipette or syringe may also
24、 be used todeliver the 23-L volume of the solution of explosives accu-rately.5. Procedure5.1 Preparation of Workspace:5.1.1 Cover table of bench surface with clean, absorbent,disposable material.5.1.2 Care should be taken not to contaminate sampleswipes. Handling the swipes with either unused gloves
25、 or cleantweezers is recommended. It is particularly important not totouch the target area of the swipe.5.1.3 Provide convenient and appropriate means of disposalof used test swipes and other consumables.5.1.4 Four swipe supports are needed. Each support willprovide a means for allowing the alcohol
26、solutions to evaporatecompletely from the swipe without losses to other surfaces.Label each of the four swipe supports for the identity of theexplosive or blank solution to be tested for exclusive use withthat solution. This will prevent cross-contamination of theexplosives on the holder.5.1.5 In th
27、e case in which the sample and blank swipes arenot used immediately, have labeled containers ready to hold theprepared test swipes that are of an appropriate size, are clean,and have covers. Glass or metal containers (including alumi-num foil) are appropriate for this task.5.1.6 The use of chemicall
28、y resistant nitrile gloves isrecommended for handling of test solutions.5.2 Preparation of Test Swipes:5.2.1 Place the test swipes properly on the labeled swipesupports.5.2.2 Choose one of the solutions from the test kit, ensurethe cap is closed tightly, and shake well to mix.5.2.3 When the solution
29、s are being dispensed from asqueeze bottle, sacrifice the first drop by opening the cap,holding the bottle at about a 45 angle from horizontal, andsqueeze the bottle slowly to deposit one or two drops on adisposable tissue.5.2.4 Deposit a drop at about a 45 angle from horizontal onthe test swipe wit
30、hin the target area for sample deposition asindicated by the instructions provided with the detector. Ex-amples of the target area are provided in NIST IR 7240.2Ifmore than one drop is deposited on the swipe, discard it andbegin again with a unused swipe.Alternatively, a 23-Ldrop ofthe solution from
31、 the test kit can be delivered using avolumetric pipette or syringe.5.2.5 Allow the solvent to evaporate. Wait until the solutionis visibly dry on the test swipe and the alcohol smell hasdissipated. Drying times vary from approximately 5 to 20 minor longer, depending on the test swipe material and t
32、he roomtemperature. Do not dry the swipes at temperatures above 25C(77F). Care should be taken to avoid contaminating the2Verkouteren, J., Gillen, G., Verkouteren, R. M., Fletcher, R., Etz, E., et al.,“IMS-Based Trace Explosives Detectors for First Responders,” NIST IR 7240,System Assessment and Val
33、idation for Emergency Responders , U.S. Department ofHomeland Security, Washington, DC 20528. This document is summarized on theweb page http:/saver.tamu.edu/documents.php?fl=336 IMS; ion mobility spectrometry; PETN;RDX; sample matrix; swipe; test kits; TNTE2520073FIG. 1 Explosives Detector Performa
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