APPLICATION OF ION MOBILITY SPECTROMETRY TO THE IDENTIFICATION OF TRACE LEVELS OF EXPLOSIVES IN THE PRESENCE OF COMPLEX MATRICES

Methods are described for the analysis of trace levels of explosives o n materials collected at the scene of real detonations. The methods ex ploit ion mobility spectrometry (IMS) to confirm and enhance the resul ts obtained by high performance liquid chromatography with an ultravio let detector (HPLC-UV). Solvent-extracted samples contain many interfe ring substances and are cleaned up by solid-phase extraction (SPE) pri or to HPLC fractionation. Explosive-containing HPLC fractions are anal ysed by IMS after removal of solvent by vacuum centrifuge. IMS detecti on limits for explosives, typically a few hundreds of picograms, are a t least an order of magnitude lower than those for UV detection. SPE a nd HPLC fractionation also removes interfering substances that can oth erwise suppress IMS detection. Explosives discussed are di- and trinit rotoluene, ethylene glycol dinitrate, nitroglycerin, pentaerythritol t etranitrate, hexahydro-1,3,5-trinitro-1,3,5-triazine, octahydro-1,3,5, 7-tetranitro-1,3,5,7-tetraazine, and N-methyl-N,2,4,6-tetranitroanilin e.