Analysis of the headspace composition of smokeless powders using GC-MS, GC-μECD and ion mobility spectrometry.

Smokeless powder additives are usually detected from an extraction of post-blast residues or unburned powder particles followed by chromatographic analyses. This work presents the first comprehensive study of the detection of volatile and semi-volatile additives of smokeless powders using solid phase microextraction (SPME) as a sampling and pre-concentration technique. The goal of this study is to generate a list of compounds that can be used as target compounds for the vapor phase detection of smokeless powders. Sixty-five smokeless powders were studied using laboratory-based gas chromatography techniques and a field deployable ion mobility spectrometer (IMS). The detection of diphenylamine, ethyl and methyl centralite, 2,4-dinitrotoluene, diethyl and dibutyl phthalate by IMS is suggested as a method to indicate the presence of smokeless powders. A previously reported SPME-IMS analytical approach facilitates rapid sub-nanogram detection of the vapor phase components of smokeless powders. The analyte mass present in the vapor phase was sufficient for a SPME fiber to extract and concentrate most analytes at amounts above the detection limits of both the GC and the IMS methods. Analysis of 65 different smokeless powder samples revealed that diphenylamine was present in the headspace of 96% of the powders studied. Ethyl centralite was detected in 47% of the powders and 8% of the powders contained methyl centralite. Nitroglycerin was the dominant peak present in the headspace of the double-based powders. Another important headspace component, 2,4-dinitrotoluene, was detected in 44% of the powders comprising both double and single-based powders. Static headspace SPME of small amounts (∼100 mg) of smokeless powder samples for ∼5 min at room temperature resulted in the successful detection of the headspace components, demonstrating the applicability of the technique for field detection of smokeless powders using IMS as a detector.