Headspace sampling of smokeless powder odor in a dynamic airflow context

Abstract

Biological detection is leveraged within the fields of security screening and criminal investigations. Military and law enforcement personnel utilize canine teams in a range of different applications to detect explosives and narcotics. Due to the ever-changing materials encountered during routine field operations, it is imperative to have an optimal training regimen reflective of current target odor needs. Hence, the chemical understanding of target odor concentrations and subsequent means of odor delivery are essential in canine team training. Using double base smokeless powder as the target odor, this study evaluates the feasibility of presenting an explosive odor using an olfactometer. Furthermore, this study bridges instrumental validation for confirmation and understanding of odor chemical composition as well as persistence of odor over time. Instrumental parameter optimization included analysis of optimal solid phase microextraction fiber chemistry of target odor as a function of peak area response using gas chromatography-mass spectrometry (GC–MS). Studies were conducted directly over the headspace of the target odor and using the olfactometer as the dynamic airflow device for comparison purposes. Previously established volatile organic compounds from smokeless powders were detected, and comparison between non-airflow vs. airflow sampling was achieved. Results indicate a polyacrylate (PA) SPME fiber is optimal for specific detection of diphenylamine when subjected to dynamic airflow. Furthermore, sampling of “blank” trials following an odor trial indicated no residual contamination via instrumental verification. Persistence of odor volatile over a nine-week period of active olfactometer sampling showed decrease concentration, thus the need for consistent monitoring for optimal canine use.