HPLC/MS2 to detect and analyse TATP and HMTD in swabs

Peroxide-based explosives such as triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) are not difficult to synthesize and synthesis can be performed starting from readily available basic chemicals: this led to increasing use of TATP and HMTD by terrorists Whenever there is the need of collecting traces of explosives, both post blast and post transfer, surface sampling plays a critical role, especially because only reasonably small objects can be sent to a laboratory to be analyzed. Traces can also be searched on hands of suspect, where they can disappear faster than from objects. In this work TATP and HMTD were synthesized and spiked solutions or aliquots of a few milligrams of explosive compounds were then spread on different surfaces (e.g. floors, tables) or used in handling tests. Three different swabbing systems were used: dry paper swabs, cotton swabs wetted with propan-2-ol and a commercial swab, pre-wetted with propan-2-ol and water (7:3). A simple solvent extraction procedure from swab was developed with quantitative recoveries. Paper and commercial swabs were used also to sample a metal plate, where a small charge of about 4 g of TATP was detonated. Both ESI and APCI ion sources were exploited for better ionization and fragmentation condition of analytes. All the three swabbing systems gave some positive results. The developed method was validated and showed its suitability to be used in real cases, allowing TATP detection in several simulations. Confirmation by HPLC/MS2 was essential to give proper forensic identification of analytes and low limits of detection were reached.