Abstract:

The suitability of head space SPME (solid phase micro extraction) sampling for non-invasive detection of organic explosives at the crime scene is demonstrated. Vacuum outlet GC -MS is used for the analysis of the organic explosives materials absorbed on the SPME fiber. With this method low elution temperatures and short run times are achieved. Efficient SPME sampling is restricted to volatile and semi volatile organic explosives with vapor pressures equal to or higher than TNT (2,4,6 -trinitrotoluene ). The methodology is very suited for the non -invasive detection of the relatively volatile and instable compound TATP (triacetone-triperoxide ). This work shows that the realization of a static head space with a minimized volume provides optimal sensitivity. Sensitivity is also strongly affected by the ambient temperature at the crime scene. At given volume and sampling time the amount absorbed at the SPME fiber increases with temperature due to non -equilibrium effects. With appropriate containers and holders, SPME fibers can be effectively analyzed up to 3 days after sampling.

Key words: explosives, non-invasive detection, HS-SPME, vacuum outlet GC-MS