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Two-temperature preparation method for PDMS-based canine training aids for explosives



William A. MacCrehan, Mimy Young, Michele M. Schantz, T C. Angle, Paul Waggoner, Terrance Fisher


Training aids based on vapor capture-and-release into a flexible polymer, polydimethylsiloxane (PDMS), have proven successful in canine detection of explosives that have volatile or semi- volatile odorants. To enhance the rate of odor capture for less volatile targets, two temperatures are used for aid preparation. By using an elevated temperature for the target explosive, the amount of vapor is enhanced, resulting the production of more of the characteristic odor profile. The polymeric adsorbent is maintained at a cool temperature, favoring vapor capture. The success of this two-temperature approach is demonstrated for the low volatility explosive TNT using SPME (solid-phase microextraction) headspace analysis. In addition, the effect of using two temperatures on preparing training aids based on TNT and its more volatile impurities 2,4-DNT and 2,6-DNT are evaluated in canine trials. A protocol to minimize the non-target odors in the polymer is presented. In addition, schlieren videography helps to visualize the transport behavior of such heavier-than-air targets released by the training aids.
Forensic Chemistry


Polydimethylsiloxane (PDMS), PDMS odor-capture-and-release, canine training aid, TNT, 2, 4-DNT, 2, 6-DNT


MacCrehan, W. , Young, M. , Schantz, M. , Angle, T. , Waggoner, P. and Fisher, T. (2020), Two-temperature preparation method for PDMS-based canine training aids for explosives, Forensic Chemistry, [online], (Accessed May 22, 2024)


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Created October 7, 2020, Updated July 28, 2021