This study demonstrates the use of solid-phase microextraction (SPME) to extract and pre-concentrate volatile signatures (odors) from static air above plastic explosive samples, followed by detection using ion mobility spectrometry (IMS).optimized to detect the volatile, non-energetic components rather than the energetic materials.
Of the common explosives used in terrorist bombings, plastic explosives have often been used because they can be molded for concealment. Security agencies have encouraged researchers and manufacturers to develop and commercialize systems that can detect plastic explosives at security checkpoints. The current study uses a different approach in this effort when compared to current vapor-detection systems. Instead of focusing on the detection of the energetic materials, the IMS detector is optimized and configured at new operating conditions so as to detect the volatile components extracted in the headspace air above the plastic explosive. The volatiles emitted from the explosive samples can be compounds such as impurities, solvents, by-products, degradation products, and/or raw materials. For the first time, headspace sampling and detection of Detasheet, Semtex H, and C4 are reported. This was achieved by using SPME-IMS operating under one universal setting with limits of detection ranging from 1.5 to 2.5 ng for the target volatile signatures. The target signature compound a-butyl acetate and the taggant DMNB are associated with untagged and tagged Detasheet explosives, respectively. Cyclohexanone and DMNB are associated with tagged C4 explosives. DMNB is linked to tagged Sentex H explosives. In the headspace inside a glass vial containing 1 g of explosive, just over 20 ng of the target signatures can be extracted by the SPME fiber, followed by IMS detection. 5 figures, 6 tables, and 32 references