ASTM E2520-07
(Practice)Standard Practice for Verifying Minimum Acceptable Performance of Trace Explosive Detectors
Standard Practice for Verifying Minimum Acceptable Performance of Trace Explosive Detectors
SIGNIFICANCE AND USE
The practice may be used to accomplish several ends: to compare detectors before purchase; as a demonstration by the vendor that the equipment is performing properly to a minimal standard; or for a periodic verification of detector performance after purchase.
This practice establishes the minimum performance that is required for a detector to be considered effective in the detection of trace explosives. An explosives detector is considered to have “minimum acceptable performance” when it has passed all of the evaluation tests without a failure.
This practice uses three explosive compounds—RDX, PETN, and TNT—that are used to represent nitro-based compounds having a range of physical and chemical properties. The concentrations of the solutions of explosive have been determined to be sufficient to provide a positive detector alarm signal. In time, other compounds may be added or substituted into this practice as detection priorities dictate.
This practice was developed using IMS-based trace explosives detectors, but this practice should also be applicable to any explosives detector designed to analyze trace levels of high-explosive compounds collected on swipes.
This practice does not include procedures to test for compounds that may interfere with detector performance.
This practice does not test the minimum limit of detection or the dynamic range of the trace explosives detector.
This practice does not test for compounds other than high explosives.
This practice only evaluates the response of the detector to traces of pure explosive compounds.
SCOPE
1.1 This practice is primarily intended to assist first responders and security screeners in verifying the minimum acceptable performance of detectors used to identify traces of high explosives such as cyclotrimethylene trinitramine (RDX), pentaerythritol tetranitrate (PETN), and trinitrotoluene (TNT). These explosive detectors may be based on, but are not limited to, ion mobility spectrometry (IMS).
1.2 This practice is used to evaluate the detector response to evaporated residues of low-concentration solutions of explosive compounds placed on test swipes. The solutions used for this evaluation are prepared in a suitable organic solvent and contain a single high explosive.
1.3 This practice does not address or use sampling procedures common to the use of trace explosive detectors. It only tests the response of the detector once a test swipe has been successfully introduced into the explosive detector.
1.4 This practice does not evaluate the effect of contaminants or interferences that may be encountered in sampling for trace explosives in the field.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E2520 − 07
StandardPractice for
Verifying Minimum Acceptable Performance of Trace
Explosive Detectors
This standard is issued under the fixed designation E2520; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.1.2 calibration, n—act of providing the detector with a
known substance so that it may be adjusted to identify
1.1 This practice is primarily intended to assist first re-
explosive compounds correctly.
sponders and security screeners in verifying the minimum
2.1.2.1 Discussion—Manufacturers of explosives detectors
acceptable performance of detectors used to identify traces of
often provide calibration swipes. In an ion mobility spectrom-
high explosives such as cyclotrimethylene trinitramine (RDX),
etry (IMS) instrument, calibration allows the instrument to
pentaerythritol tetranitrate (PETN), and trinitrotoluene (TNT).
adjust the present values of the mobility (or drift) time of the
These explosive detectors may be based on, but are not limited
calibrant to the most current conditions. For explosives detec-
to, ion mobility spectrometry (IMS).
tors based on mass spectrometry (MS), calibration is often
1.2 This practice is used to evaluate the detector response to
called tuning. Some IMS and MS explosives detectors may
evaporated residues of low-concentration solutions of explo-
have built-in materials and software to perform calibration
sive compounds placed on test swipes. The solutions used for
automatically.
this evaluation are prepared in a suitable organic solvent and
2.1.3 instrument blank swipe, n—unused swipe freshly re-
contain a single high explosive.
moved from the container provided by the manufacturer.
1.3 This practice does not address or use sampling proce-
2.1.4 performance evaluation solution, n—dilute solution of
dures common to the use of trace explosive detectors. It only
a single explosive compound dissolved in a semivolatile
tests the response of the detector once a test swipe has been
solvent.
successfully introduced into the explosive detector.
2.1.5 process blank swipe, n—sample swipe that has been
1.4 This practice does not evaluate the effect of contami-
dosed with the blank solution.
nants or interferences that may be encountered in sampling for
2.1.6 sample swipe, n—pads that are made from various
trace explosives in the field.
types of materials, including fabric and paper, that are offered
by the equipment manufacturer to collect particle samples for
1.5 The values stated in SI units are to be regarded as
use in trace explosives detectors.
standard. No other units of measurement are included in this
standard. 2.1.6.1 Discussion—Also referred to as sample traps by
some manufacturers of trace explosives detectors.
1.6 This standard does not purport to address all of the
2.1.7 swipe support, n—holder for the sample swipe that
safety concerns, if any, associated with its use. It is the
suspends the swipe preventing contact of the back side of the
responsibility of the user of this standard to establish appro-
sampling area with any surface that might wick away drops of
priate safety and health practices and determine the applica-
solution.
bility of regulatory limitations prior to use.
2.1.8 test kit, n—setofindividualsolutionsoftheexplosives
2. Terminology
and a blank solution to be used for the evaluation of explosives
detector performance.
2.1 Definitions of Terms Specific to This Standard:
2.1.8.1 Discussion—The test kit may also include holders
2.1.1 blank solution, n—semivolatile solvent that does not
used for supporting the sample swipes for solution application.
contain trace explosives to which the detector is sensitive.
2.1.9 test swipe, n—sample swipe that has been dosed with
one of the performance evaluation solutions and dried.
This practice is under the jurisdiction of ASTM Committee E54 on Homeland
2.1.10 trace explosives detector, n—an instrument designed
Security Applications and is the direct responsibility of Subcommittee E54.01 on
to detect trace amounts (micrograms or less) of explosive
CBRNE Sensors and Detectors.
compounds.
Current edition approved Feb. 1, 2007. Published March 2007. DOI: 10.1520/
E2520-07. 2.1.10.1 Discussion—In the context of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2520 − 07
practice, a trace explosives detector will require the use of a 1.0 mg/L or ≈23 ng per drop; and PETN concentration: 1.7
swipe sample collector. These detectors are commonly based mg/L or ≈40 ng per drop. The volume of solution of explosive
on, but not limited to, ion mobility spectrometry. delivered by a single drop is based on an average drop volume
of23µLdispensedbyholdingthebottleatapproximatelya45°
2.2 Acronyms:
angle. A volumetric pipette or syringe may also be used to
2.2.1 IMS, n—ion mobility spectrometry
deliver the 23-µL volume of the solution of explosives accu-
2.2.2 MS, n—mass spectrometry
rately.
2.2.3 PETN, n—pentaerythritol tetranitrate
5. Procedure
2.2.4 RDX, n—cyclotrimethylene trinitramine
5.1 Preparation of Workspace:
2.2.5 TNT, n—trinitrotoluene
5.1.1 Cover table of bench surface with clean, absorbent,
disposable material.
3. Significance and Use
5.1.2 Care should be taken not to contaminate sample
3.1 The practice may be used to accomplish several ends: to
swipes. Handling the swipes with either unused gloves or clean
compare detectors before purchase; as a demonstration by the
tweezers is recommended. It is particularly important not to
vendor that the equipment is performing properly to a minimal
touch the target area of the swipe.
standard; or for a periodic verification of detector performance
5.1.3 Provide convenient and appropriate means of disposal
after purchase.
of used test swipes and other consumables.
3.2 This practice establishes the minimum performance that
5.1.4 Four swipe supports are needed. Each support will
is required for a detector to be considered effective in the
provideameansforallowingthealcoholsolutionstoevaporate
detection of trace explosives. An explosives detector is con-
completely from the swipe without losses to other surfaces.
sidered to have “minimum acceptable performance” when it
Label each of the four swipe supports for the identity of the
has passed all of the evaluation tests without a failure.
explosive or blank solution to be tested for exclusive use with
that solution. This will prevent cross-contamination of the
3.3 This practice uses three explosive compounds—RDX,
explosives on the holder.
PETN, and TNT—that are used to represent nitro-based
5.1.5 In the case in which the sample and blank swipes are
compounds having a range of physical and chemical proper-
notusedimmediately,havelabeledcontainersreadytoholdthe
ties.Theconcentrationsofthesolutionsofexplosivehavebeen
prepared test swipes that are of an appropriate size, are clean,
determined to be sufficient to provide a positive detector alarm
and have covers. Glass or metal containers (including alumi-
signal. In time, other compounds may be added or substituted
num foil) are appropriate for this task.
into this practice as detection priorities dictate.
5.1.6 The use of chemically resistant nitrile gloves is
3.4 This practice was developed using IMS-based trace
recommended for handling of test solutions.
explosives detectors, but this practice should also be applicable
5.2 Preparation of Test Swipes:
to any explosives detector designed to analyze trace levels of
5.2.1 Place the test swipes properly on the labeled swipe
high-explosive compounds collected on swipes.
supports.
3.5 This practice does not include procedures to test for
5.2.2 Choose one of the solutions from the test kit, ensure
compounds that may interfere with detector performance.
the cap is closed tightly, and shake well to mix.
3.6 This practice does not test the minimum limit of
5.2.3 When the solutions are being dispensed from a
detection or the dynamic range of the trace explosives detector.
squeeze bottle, sacrifice the first drop by opening the cap,
holding the bottle at about a 45° angle from horizontal, and
3.7 This practice does not test for compounds other than
squeeze the bottle s
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