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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.

General Information

Status
Historical
Publication Date
31-Jan-2007
ICS
13.230 - Explosion protection
Technical Committee
E54 - Homeland Security Applications
Drafting Committee
E54.01 - CBRNE Detection and CBRN Protection
Current Stage
Ref Project

Relations

Referred By
ASTM F3438-21 - Standard Guide for Detection and Quantification of Cleaning Markers (Analytes) for the Validation of Cleaning Methods for Reusable Medical Devices
Effective Date
01-Feb-2007
Referred By
ASTM E2771-11(2019) - Standard Terminology for Homeland Security Applications
Effective Date
01-Feb-2007
Referred By
ASTM E2677-20 - Standard Test Method for Estimating Limits of Detection in Trace Detectors for Explosives and Drugs of Interest
Effective Date
01-Feb-2007
Referred By
ASTM F3321-19 - Standard Guide for Methods of Extraction of Test Soils for the Validation of Cleaning Methods for Reusable Medical Devices
Effective Date
01-Feb-2007

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ASTM E2520-07 - Standard Practice for Verifying Minimum Acceptable Performance of Trace Explosive DetectorsASTM E2520-07 - Standard Practice for Verifying Minimum Acceptable Performance of Trace Explosive Detectors
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ASTM E2520-07 - Standard Practice for Verifying Minimum Acceptable Performance of Trace Explosive Detectors
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E2520 − 07
StandardPractice for
Verifying Minimum Acceptable Performance of Trace
1
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.
1
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
1

---------------------- Page: 1 ----------------------
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 m
...

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5.1 This practice may be used to accomplish several ends: to establish a worldwide frame of reference for terminology, metrics, and procedures for reliably determining trace detection performance of ETDs; as a demonstration by the vendor that the equipment is operating properly to a specified performance score; for a periodic verification by the user of detector performance after purchase; and as a generally-acceptable template adaptable by international agencies to specify performance requirements, analytes and dosing levels, background challenges, and operations.  
5.2 It is expected that current ETD systems will exhibit wide ranges of performance across the diverse explosive types and compounds considered. As in previous versions, 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 attained a test score of at least 80.
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1.1 This practice may be used for measuring, scoring, and improving the overall performance of detectors that alarm on traces of explosives on swabs. These explosive trace detectors (ETDs) may be based on, but are not limited to, chemical detection technologies such as ion mobility spectrometry (IMS) and mass spectrometry (MS).  
1.2 This practice considers instrumental (post-sampling) trace detection performance, involving specific chemical analytes across eight types of explosive formulations in the presence of a standard background challenge material. This practice adapts Test Method E2677 for the evaluation of limit of detection, a combined metric of measurement sensitivity and repeatability, which requires ETDs to have numerical responses.  
1.3 This practice considers the effective detection throughput of an ETD by factoring in the sampling rate, interrogated swab area, and estimated maintenance requirements during a typical eight hour shift.  
1.4 This practice does not require, but places extra value on, the specific identification of targeted compounds and explosive formulations.  
1.5 The functionality of multi-mode instruments (those that may be switched between detection of trace explosives, drugs of interest, chemical warfare agents, and other target compounds) may also be tested. A multi-mode instrument under test shall be set to the mode that optimizes operational conditions for the detection of trace explosives. This practice requires the use of a single set of ETD operational settings for calculating a system test score based on the factors described in 1.2, 1.3, and 1.4. A minimum acceptable score is derived from criteria established in Practice E2520 – 07, and an example of such a test is presented in Appendix X1 (Example 2).  
1.6 Intended Users—ETD developers and manufacturers, testing laboratories, and international agencies responsible for enabling effective deterrents to terrorism.  
1.7 Actual explosives as test samples would be preferable, but standard explosive formulations are not widely available, nor are methods for depositing these quantitatively and realistically on swabs. This practice considers sixteen compounds that are available from commercial suppliers. This does not imply that only these sixteen are important to trace detection. Most ETDs are able to detect many other compounds, but these are either chemically similar (hence redundant) to the ones considered, or are unavailable from commercial suppliers for reasons of stability and safety. Under typical laboratory practices, the sixteen compounds considered are safe to handle in the quantities used.  
1.8 This practice is not intended to replace any current standard procedure employed by agencies to test performance of ETDs for specific applications. Those procedures may be more rigorous, use different compounds or actual explosive formulations, employ different or more realistic background...

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Standard Test Method for Estimating Limits of Detection in Trace Detectors for Explosives and Drugs of Interest

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5.1 Commercial trace detectors are used by first responders, security screeners, the military, and law enforcement to detect and identify explosive threats and drugs of interest quickly. These trace detectors typically operate by detecting chemical agents in residues and particles sampled from surfaces and can have detection limits for some compounds extending below 1 ng. A trace detector is set to alarm when its response to any target analyte exceeds a programmed threshold level for that analyte. Factory settings of such levels typically balance sensitivity and selectivity assuming standard operating and deployment conditions.  
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Note 2: There are several different “detection limits” that can be determined for analytical procedures. These include the minimum detectable value, the instrument detection limit, the method detection limit, the limit of recognition, the limit of quantitation, and the minimum consistently detectable amount. Even when the same terminology is used, there can be differences in the LOD according to nuances in the definition used, the assumed response model, and the type of noise contributing to the measurement.  
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1.1 In harmony with the Joint Committee for Guides in Metrology (JCGM) and detection concepts of the International Union of Pure and Applied Chemistry (IUPAC) (1, 2)2, this test method uses a series of replicated measurements of an analyte at dosage levels giving instrumental responses that bracket the critical value, a truncated normal distribution model, and confidence bounds to establish a standard for estimating practical and statistically robust limits of detection.
Note 1: Other standards are available that evaluate the general performance of detection technologies for various analytes in complex matrices (for example, Practice E2520).  
1.2 Here, the limit of detection (LOD90) for a compound is defined to be the lowest mass of that compound deposited on a sampling swab for which there is 90 % confidence that a single measurement in a particular trace detector will have a true detection probability of at least 90 % and a true nondetection probability of at least 90 % when measuring a process blank sample.  
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5.1 This standard is intended to provide guidance on the deployment of blast resistant trash receptacles that focuses on the mitigation of human injury. It is not in general intended to provide guidance on the protection of structures in the vicinity of where the blast resistant trash receptacles are deployed.  
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5.1 This test method provides a procedure for performing laboratory tests to evaluate relative deflagration parameters of dusts.  
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5.4 If too weak an ignition source is used, the measured MEC would be higher than the “true” value. This is an ignitability limit rather than a flammability limit, and the test could be described as “underdriven.” Ideally, the ignition energy is increased until the measured MEC is independent of ignition energy. However, at some point the ignition energy may become too strong for the size of the test chamber, and the system becomes “overdriven.” When the ignitor flame becomes too large relative to the chamber volume, a test could appear to result in an explosion, while it is actually just dust burning in the ignitor flame with no real propagation beyond the ignitor.  
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FIG. 3 b Untested Nylon (PA, polyamide) Valve Seat (10X magnification) (c...
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1.1 This test method describes a method to determine the relative sensitivity of nonmetallic materials (including plastics, elastomers, coatings, etc.) and components (including valves, regulators flexible hoses, etc.) to dynamic pressure impacts by gases such as oxygen, air, or blends of gases containing oxygen.  
1.2 This test method describes the test apparatus and test procedures employed in the evaluation of materials and components for use in gases under dynamic pressure operating conditions up to gauge pressures of 69 MPa and at elevated temperatures.  
1.3 This test method is primarily a test method for ranking of materials and qualifying components for use in gaseous oxygen. The material test method is not necessarily valid for determination of the sensitivity of the materials in an “as-used” configuration since the material sensitivity can be altered because of changes in material configuration, usage, and service conditions/interactions. However, the component testing method outlined herein can be valid for determination of the sensitivity of components under service conditions. The current provisions of this method were based on the testing of components having an inlet diameter (ID bore) less than or equal to 14 mm (see Note 1).  
1.4 A 5 mm Gaseous Fluid Impact Sensitivity (GFIS) test system and a 14 mm GFIS test system are described in this standard. The 5 mm GFIS system is utilized for materials and components that are directly attached to a high-pressure source and have minimal volume between the material/component and the pressure source. The 14 mm GFIS system is utilized for materials and components that are attached to a high pressure source through a manifold or other higher volume or larger sized connection. Other sizes than these may be utilized but no attempt has been made to characterize the thermal profiles of other volumes and geometries (see Note 1).
Note 1: The energy delivered by this t...

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ASTM
ASTM E2520-21(Practice)
Standard Practice for Measuring and Scoring Performance of Trace Explosive Chemical Detectors

SIGNIFICANCE AND USE
5.1 This practice may be used to accomplish several ends: to establish a worldwide frame of reference for terminology, metrics, and procedures for reliably determining trace detection performance of ETDs; as a demonstration by the vendor that the equipment is operating properly to a specified performance score; for a periodic verification by the user of detector performance after purchase; and as a generally-acceptable template adaptable by international agencies to specify performance requirements, analytes and dosing levels, background challenges, and operations.  
5.2 It is expected that current ETD systems will exhibit wide ranges of performance across the diverse explosive types and compounds considered. As in previous versions, 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 attained a test score of at least 80.
SCOPE
1.1 This practice may be used for measuring, scoring, and improving the overall performance of detectors that alarm on traces of explosives on swabs. These explosive trace detectors (ETDs) may be based on, but are not limited to, chemical detection technologies such as ion mobility spectrometry (IMS) and mass spectrometry (MS).  
1.2 This practice considers instrumental (post-sampling) trace detection performance, involving specific chemical analytes across eight types of explosive formulations in the presence of a standard background challenge material. This practice adapts Test Method E2677 for the evaluation of limit of detection, a combined metric of measurement sensitivity and repeatability, which requires ETDs to have numerical responses.  
1.3 This practice considers the effective detection throughput of an ETD by factoring in the sampling rate, interrogated swab area, and estimated maintenance requirements during a typical eight hour shift.  
1.4 This practice does not require, but places extra value on, the specific identification of targeted compounds and explosive formulations.  
1.5 The functionality of multi-mode instruments (those that may be switched between detection of trace explosives, drugs of interest, chemical warfare agents, and other target compounds) may also be tested. A multi-mode instrument under test shall be set to the mode that optimizes operational conditions for the detection of trace explosives. This practice requires the use of a single set of ETD operational settings for calculating a system test score based on the factors described in 1.2, 1.3, and 1.4. A minimum acceptable score is derived from criteria established in Practice E2520 – 07, and an example of such a test is presented in Appendix X1 (Example 2).  
1.6 Intended Users—ETD developers and manufacturers, testing laboratories, and international agencies responsible for enabling effective deterrents to terrorism.  
1.7 Actual explosives as test samples would be preferable, but standard explosive formulations are not widely available, nor are methods for depositing these quantitatively and realistically on swabs. This practice considers sixteen compounds that are available from commercial suppliers. This does not imply that only these sixteen are important to trace detection. Most ETDs are able to detect many other compounds, but these are either chemically similar (hence redundant) to the ones considered, or are unavailable from commercial suppliers for reasons of stability and safety. Under typical laboratory practices, the sixteen compounds considered are safe to handle in the quantities used.  
1.8 This practice is not intended to replace any current standard procedure employed by agencies to test performance of ETDs for specific applications. Those procedures may be more rigorous, use different compounds or actual explosive formulations, employ different or more realistic background...

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ASTM E2677-20(Test Method)
Standard Test Method for Estimating Limits of Detection in Trace Detectors for Explosives and Drugs of Interest

SIGNIFICANCE AND USE
5.1 Commercial trace detectors are used by first responders, security screeners, the military, and law enforcement to detect and identify explosive threats and drugs of interest quickly. These trace detectors typically operate by detecting chemical agents in residues and particles sampled from surfaces and can have detection limits for some compounds extending below 1 ng. A trace detector is set to alarm when its response to any target analyte exceeds a programmed threshold level for that analyte. Factory settings of such levels typically balance sensitivity and selectivity assuming standard operating and deployment conditions.  
5.2 The LOD for a substance is commonly accepted as the smallest amount of that substance that can be reliably detected in a given type of medium by a specific measurement process (2). The analytical signal from this amount shall be high enough above ambient background variation to give statistical confidence that the signal is real. Methods for determining nominal LOD values are well known but pitfalls exist in specific applications. Vendors of trace detectors often report detection limits for only a single compound without defining the meaning of terms or reference to the method of determination.
Note 2: There are several different “detection limits” that can be determined for analytical procedures. These include the minimum detectable value, the instrument detection limit, the method detection limit, the limit of recognition, the limit of quantitation, and the minimum consistently detectable amount. Even when the same terminology is used, there can be differences in the LOD according to nuances in the definition used, the assumed response model, and the type of noise contributing to the measurement.  
5.3 When deployed, the individual performance of a trace detector (for example, realistic LODs) is influenced by: (1) manufacturing differences, history, and maintenance; (2) operating configurations (for example, thermal desorption tem...
SCOPE
1.1 In harmony with the Joint Committee for Guides in Metrology (JCGM) and detection concepts of the International Union of Pure and Applied Chemistry (IUPAC) (1, 2)2, this test method uses a series of replicated measurements of an analyte at dosage levels giving instrumental responses that bracket the critical value, a truncated normal distribution model, and confidence bounds to establish a standard for estimating practical and statistically robust limits of detection.
Note 1: Other standards are available that evaluate the general performance of detection technologies for various analytes in complex matrices (for example, Practice E2520).  
1.2 Here, the limit of detection (LOD90) for a compound is defined to be the lowest mass of that compound deposited on a sampling swab for which there is 90 % confidence that a single measurement in a particular trace detector will have a true detection probability of at least 90 % and a true nondetection probability of at least 90 % when measuring a process blank sample.  
1.3 This particular test method was chosen on the basis of reliability, practicability, and comprehensiveness across tested trace detectors, analytes, and deployment conditions. The calculations involved in this test method are published elsewhere (3), and are performed through an interactive web-based calculator available on the National Institute of Standards and Technology (NIST) site: https://www-s.nist.gov/loda.  
1.4 Intended Users—Trace detector developers and manufacturers, vendors, testing laboratories, and agencies responsible for public safety and enabling effective deterrents to terrorism.  
1.5 While this test method may be applied to any detection technology that produces numerical output, the method is especially applicable to measurement systems influenced by heterogeneous error sources that lead to non-linear and heteroskedastic dose/response relationships and truncated or censored respons...

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