U.S. Department of Defense


Date of this Version



Forensic Chemistry 4 (2017), pp. 19–31.


U.S. government work.


Homemade explosive (HME) materials commonly take the form of binary, ammonium nitrate-based explosives, and are a challenge to detect due to the low volatility of ammonium nitrate, the great variation in fuel sources, and the complex environment in which detection takes place. Vapor detection in the form of detector canines overcomes these and other obstacles, and has proven to be a highly effective mode of detection. Due to inherent safety precautions associated with working with HMEs, experienced detector canines often lack the frequency of training on HME material necessary to remain proficient. For this reason, the Mixed Odor Delivery Device (MODD) was designed allowing canines to train on the odor of mixed explosives while keeping the HME components separate and unmixed, thus alleviating the safety requirements for handling, storing, and transporting explosives. Experiments across multiple investigative strategies were carried out to evaluate and characterize the vapor distribution in the MODD including computational modeling, analytical testing, and field trials. All testing indicated the MODD accurately provides uniformly mixed HME vapor at detectable levels from separated HME components.