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With the ever-increasing threat of improvised explosive devices (IEDs) and homemade explosives (HME) both domestically and abroad, detection of explosives and explosive related materials is an area of urgent importance for preventing terrorist activities around the globe. Canines are a common biological detector used in explosive detection due to their enhanced olfactory abilities, high mobility, efficient standoff sampling, and optimal identification of vapor sources. While other sensors based on different principles have emerged, an important concept for the rapid field detection of explosives is understanding key volatile organic compounds (VOCs) associated with these materials. Explosive detection technology needs to be on par with a large number of threats including an array of explosive materials as well as novel chemicals used in the manufacture of IEDs. Within this much needed area of research for law enforcement and homeland security applications, several studies have sought to understand the explosive odor profile from a range of materials. This review aims to provide a foundational overview of these studies to provide a summary of instrumental analysis to date on the various types of explosive odor profiles evaluated focusing on the experimental approaches and laboratory techniques utilized in the chemical characterization of explosive vapors and mixtures. By expanding upon these concepts, a greater understanding of the explosive vapor signature can be achieved, providing for enhanced chemical and biological sensing of explosive threats as well as expanding upon existing laboratory-based models for continued sensor development. [Display omitted] •Detection of explosives and their related materials is an area of urgent importance.•Understanding of volatile organic compounds (VOCs) is key to rapid field detection of explosives.•Enhanced olfactory abilities and high mobility makes canines an excellent tool in biological detection of explosives.•Explosive detection technology must stay up to date with current and expanding threats.•Experimental techniques provide understanding of explosive vapor odor signatures for enhanced sensor development.

Despite numerous instrumental achievements, canines are still considered the most effective field method for explosive detection. However, due to strict explosive regulations and safety requirements, it can be a challenge for agencies with “bomb dogs” to train using neat explosive materials. This establishes a need for non-explosive canine training aids with the same volatile component profiles as the explosives that they represent. In order to compare mimic materials to their explosive counterparts, a technique must be established that not only allows for identification of volatile compounds but also can monitor changes in the headspace profile over time with respect to time and temperature. The Automated Training Aid Simulation using SPME (or ATASS) was developed for that purpose. As described, ATASS was used to observe changes in the volatile profile of three explosives (Composition C-4, 2,4-dinitrotoluene (DNT), and triacetone triperoxide (TATP)) and respective prototype training materials (0.1% by mass C-4, 1% by mass 2,4-DNT, and 1% by mass TATP). Samples were prepared in vials and metal tins within a gallon (≈3785 mL) paint can to simulate common field techniques for canine training. Monitoring these materials in real time provides a better understanding of the major volatile components present and how the relative abundances of these components can change over time. The results presented indicate that ATASS successfully allows for a sufficient comparison between explosive and non-explosive training materials.