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A Fistful of Dynamite – Minimizing Degradation of Nitroglycerin in a Hot GC Injector

21 Feb 2009

Amanda Rigdon and I presented “Optimization of Explosives Analysis by GC and LC” at the recent Academy of Forensic Sciences Annual Meeting (February 16-21, Denver, Colorado). To reduce analysis time and thermal degradation, “low pressure” or “vacuum outlet” GC-MS was used, which promotes lower elution temperatures. However, effective injection of explosives is the first step to their successful GC analysis.

Nitrate esters (EGDN, PGDN, nitroglycerin, and PETN) are particularly prone to thermal degradation during hot splitless injection. The figure shows that by lowering injector temperature and avoiding liner packing, the thermal degradation of nitroglycerin can be minimized. Keep in mind though that a lower injector temperature might lead to ineffective transfer of less volatile explosives like RDX and Tetryl.

Other options for introducing explosives in GC include direct injection and on-column injection. Restek has liners for both, so contact me for a recommendation.