Authors: Katherine D. Castro, Reagan M. Bridges, Tyler Roberts, Lauryn E. DeGreeff

Hazardous materials such as explosives and drugs pose a threat to public safety both in their potential to cause harm through detonation or ingestion but also to those who need to transport and identify these materials. Canines are often selected in the detection of illicit materials due to their many abilities. Not only do their noses contain up to 300 million olfactory receptors allowing for high sensitivity in the parts per billion and trillion levels, but their ability to move and trace an odor to its source allows for a quick removal of a hazard. Canine detection is also non-invasive which prevents direct contact of a material, lessening chances of harm. However, to train a good canine, they must have clean training materials that accurately represent the odor of their targets. Canine training aids are prone to contamination due to the nature of canine training as the aid must be opened to the air during a training session putting the material at risk of contamination. Contaminated training aids may lower a canine’s detection proficiency to below set standards and, more importantly, risk missing and alert for a hazard. In this study, the contamination of canine training aids was explored with laboratory-controlled contamination as well as more complex contaminated samples used in the field. In the laboratory-controlled experiments, explosive and drug analytes were exposed to three contaminants over increasing periods of time and analyzed by headspace solid phase microextraction with gas chromatography mass spectrometry (HS-SPME GC-MS) to determine when contamination reaches a maximum. From here, the contaminated sample was allowed to off-gas to determine when the analytes were no longer detectable by the instrument therefore leaving the headspace of the analyte. This provided information on suggested time frames for canine handlers to clean their aids after suspected contamination. Increasing in complexity, training aid surrogates were provided to canine handlers to store and handle in the same fashion as their training aids. The surrogates were exposed to the same conditions as the training aids and opened for the same amount of time during a training session. These samples were analyzed bimonthly by HS-SPME-GCMS. With this information, along with journals of each training session, we were able to determine the behavior of contaminants as they enter or exit the headspace, which materials are most prone to contamination, and the ease in which a training aid can be overcome by unwanted odors that interfere with the target odorants.