Detection of explosives residue using a novel subsampling technique for DART-HRMS analysis

Abstract

In the ensuing investigation after an explosion, determining the explosive used is of prime importance to establish investigative leads. Post-blast samples have many interferences and considerations that make quick, reliable identification a challenge. The use of a novel subsampling technique with DART-HRMS provides the ability to quickly detect and identify explosive residue after detonation. Simulated improvised explosive devices were constructed with a variety of materials and detonated with the help of the Montgomery County Fire Marshal’s Office (TX). Post-blast debris was subsequently collected and swabbed with a novel subsampling technique, utilizing filter paper. This filter paper was then introduced into the DART gas stream, with an internal standard to minimize potential false negatives. After introducing explosive residue from swabbed post-blast substrates, characteristic ions of selected constituents of smokeless powder including diphenylamine, ethyl centralite, di-n-butyl phthalate, and nitroglycerin were detected and confirmed through comparison of accurate mass measurements to theoretical exact masses. Additionally, characteristic ions of 2,4,6-trinitrotoluene (TNT) and Royal Demolition eXplosive (RDX) were also detected using this technique. Overall, the detection of characteristic ions was more successful when recovering residue from plastic compared to wood or metal, with success rates routinely at 100%. Implementing this screening technique enables rapid detection and reliable identification of explosive residue in a detonation incident. The developed subsampling technique provides practitioners with a practical method of screening post-blast debris in a laboratory setting, requiring minimal sample preparation.