Headspace Characterization of Smokeless Powders Using Thermal Desorption‐Gas Chromatography‐Mass Spectrometry for Consideration in Canine Detection Training

Abstract Explosives detection canines (K9s) are routinely utilized for non‐contact detection of smokeless powders (SP) but the distinct odor(s) used by K9s for SP detection are unknown. Here, the headspace of single base (SB) and double base (DB) SPs was collected using dynamic air sampling and characterized using thermal desorption (TD) gas chromatography coupled to mass spectrometry to identify headspace analytes. TD method parameters were optimized and the headspace analysis of 26 SPs resulted in detection of 3291 compounds. Statistical analyses were utilized to narrow down significant components and principal component analysis was used to visualize potential relationships within the data. SP samples originating from the same countries clustered together and a separation in clustering for SB and DB SPs was also observed. Unique volatile chemical compounds were identified for SB and DB SPs (15 and 10 components respectively), as well as for SPs with differing origins. Shared entities between these sample groupings were also identified which may help provide a list of compounds useful for generalization of SPs regardless of manufacturing origin or SP type. Some components identified in the headspace include nitroglycerin, diphenylamine, butyl acetate, and phthalates among others. The variance in headspace data demonstrates the complexity of SP odor profiles and reiterates the need for paired K9 detection studies to understand generalization across SPs. Further implications of this research may allow for identification of additional SP training aids for inclusion in K9 kits to broaden their exposure to a diverse set of SP odor profiles.