As part of a multiyear interagency agreement between NIST and the Office of Standards of the Department of Homeland Security, NIST is developing a series of Standard Reference Materials (SRMs) to support the detection of trace explosives. Both particulate and solution SRMs are being prepared to determine the sensitivity and reliability of handheld, tabletop, portal, and laboratory detection systems. The particulate SRMs incorporate trace amounts of real explosives on an inert support that provide properties that are consistent with fingerprint residues. Solution SRMs have concentrations of selected explosives that provide an alarm signal with most commercial detectors but are near the detection limits. ‘Best practices’ for the validation of trace explosives detectors are also being promoted through the development of ASTM International Standards.
Tens of thousands of explosive detection systems are currently deployed by federal, state, and local governments to protect the public from terrorist explosive crime. These “field” detectors are used in many locations such as at airport security checkpoints, marine terminals, loading docks, border crossings, and building entrances to detect and prevent the passage of improvised explosive devices (IEDs). To date, there are no available reference materials for trace explosives to evaluate the performance of these detectors. Providing NIST SRMs and ASTM Standards will support the optimization of instrument design and validation, as well as promote evaluation of performance prior to procurement and throughout the lifetime of the device. “Raising the bar” for detector performance will save money spent on ineffective equipment, more effectively detect terrorist acts in advance, and potentially save lives.
Additional Technical Details:
Development of SRMs for trace explosives requires a strong metrological base including research to provide accurate measurement methods and calibration. For the development of particulate SRMs that simulate residues, the investigation of suitable inert supports and protocols to incorporate the explosive materials are the initial steps. Analyte thermal stability has proven to be a critical criterion. The performance of the materials in laboratory analyses and in field measurement instruments is the final requirement. For the development of the first SRM in the series, SRM 2905 Trace Particulate Explosives, nine substrate materials were evaluated. The development of solution SRMs has required the development of sensitive analytical measurements, consideration of suitable packaging, and investigation of thermal stability. Promulgation of ASTM International Standards requires collaborative discussions with Division 637 technical staff and stakeholders in Subcommittee E54.01 Homeland Security: CBRNE Sensors and Detectors.
- SRM 2905 Trace Particulate Explosive Simulants provides trace levels of the plastic explosive Composition C4 (containing RDX and HMX) and the military explosive TNT at nominal mass fractions of 0.1 % and 0.01 % of each.
- ASTM E2520-07 Standard Practice for Verifying Minimum Acceptable Performance of Trace Explosive Detectors provides a validated protocol to evaluate commonly-deployed swipe detection systems.
- SRM 2906 Trace Explosives Calibration Solutions provides nitramine (RDX), alkyl nitrate (PETN), and aromatic nitro (TNT) explosives meeting the requirements of ASTM E2520-07.
- SRM 2907 Trace Terrorist Explosives Simulants consists of inert particles coated with Semtex 1A (which is certified for pentaerythritol tetranitrate, PETN) and triacetone triperoxide (TATP).
Image of a unit of SRM 2905 Trace Particulate Explosives showing a dispenser bottle of one of the four materials. The fluorescently-tagged material is also viewed through orange glasses while illuminated with a blue crime scene light.
October 1, 2003
Lead Organizational Unit:
Related Programs and Projects:
SRM 2905 Trace Particulate Explosive Simulants - values assigned for RDX, HMX, TNT
SRM 2906 Trace Explosives Calibration Solutions – values assigned for RDX, PETN, TNT
SRM 2907 Trace Terrorist Explosives Simulants - values assigned for PETN, TATP
A unit of SRM 2906 consists of four glass ampoules of each of the three explosives containing approximately 1 mL of the solution and four vials of the 2‑propanol solvent used to prepare the solutions. In addition, there are four labeled dropper bottles for temporary storage of the solutions once opened.
MacCrehan, W.A. and Bedner, M. “NIST Reference Materials for Explosives Analysis” Proceedings of the 8th International Symposium on the Analysis and Detection of Explosives, Public Security and Emergency Preparedness, Ottawa Canada 2004.
MacCrehan, W.A.; "Development of a NIST Trace Particulate Explosives Reference Material to Evaluate IMS Detectors," Int. J. Ion Mobil. Spectrom. 9:13–23, (2006)
MacCrehan, W.A. and Benner, B.A. “Development of NIST Standard Reference Materials for Trace Explosives Detectors” Proceedings of the 9th ISADE/4th FINEX meeting, 2007.
MacCrehan, W.; "A NIST Standard Reference Material (SRM) to Support the Detection of Trace Explosives," Anal. Chem. 81 (17):7189–7196, (2009).