NIST's SRM 2905 Addresses Trace Explosives Detectors
September 16, 2009 // Published as a news service by IHS
The National Institute of Standards and Technology (NIST), with support from the U.S. Department of Homeland Security, developed Standard Reference Material (SRM) 2905 - Trace Particulate Explosives.
The SRM helps security personnel find explosive materials and persons who have been in contact with them, according to NIST.
The SRM will help calibrate, test and develop standard best operating procedures for trace explosives detectors.
SRM 2905 consists of four different test substances designed to simulate trace residues of C-4 plastic explosives and TNT.
The substances themselves consist of inert solid particles about 20 to 30 microns in diameter. The particles were coated with explosive materials and a florescent tag, which enables the material to be seen using specially filtered optics or glasses.
Although the particles are coated with explosive material, they are incapable of exploding on their own and are safe to handle, according to William MacCrehan, NIST chemist.
Customs inspectors use walkthrough portal or tabletop-type trace explosive detectors to check international cargo shipments. Firefighters and police officers use them to evaluate "suspicious" packages.
The goal of these detectors is to collect residue particles that result from handling materials that might be used to fabricate a bomb and then evaluate the explosives content.
For example, when operating the tabletop device, security personnel use a piece of material to swab packages and bags for explosive residues.
The security officer then places the swab in a tabletop device that heats the material, separating any chemical residues that were absorbed.
Like other sensitive instruments, these machines need calibration standards to ensure they are working properly, which is the purpose of SRM 2905. The calibration materials that the vendors of these machines provide are of unknown quality, said MacCrehan.
This release is part of a larger, ongoing project to develop other wet and dry materials that simulate Semtex, gunpowder and peroxide-type explosives. MacCrehan said efforts are also underway to develop reference materials to help train bomb-sniffing dogs.
Source: National Institute of Standards and Technology (NIST).