<title>Development of particle standards for testing detection systems: mass of RDX and particle size distribution of composition 4 residues</title>

Abstract

A study has been performed to determine the mass of RDX and the particle size distribution of composition 4 residue deposited by fingerprint transfer. Particle residues of composition 4 deposited on to smooth polyethylene films were studied. Six sample sets of fifty sequential prints were examined in the study. Mass of RDX was determined by gas chromatography with electron capture detection for give sample sets. The particle size distribution of composition 4 residues was determined by microscopic examination for the sixth set. Results indicated that although there was variability across the series in the amount of RDX for a particle sample sequence number, results corroborated well with preliminary studies conducted by NRC of Canada. In a series of successive thumb prints laid down sequentially after an initial imprint on to C-4 explosive, the residue RDX contamination ranged from milligram levels for the first few prints to nanogram levels for fortieth to fiftieth print. Moreover, a log-log correlation was established between fingerprint number and mass of RDX present. Microscopic results indicated that the measured particle size distribution appears bi-modal in nature and is lognormally distributed.