Mixed Vapor Generation Device for delivery of homemade explosives vapor plumes

Abstract

While there is a large body of research on the properties and detection of traditional military high explosives and propellant low explosives, there is a dearth of research on homemade explosive (HME) materials, though they are prevalent today. The safety of working with these materials in the laboratory is the greatest limiting factor preventing HME research. A vapor delivery tool, the Mixed Vapor Generation Device (MV-Gen), was designed to safely contain the individual solid or liquid components that often compose homemade explosives vapor plumes and deliver the mixed component vapors for instrumental sampling and analysis. Within the MV-Gen, each component is separated and only the vapors mix as they are carried through the device by flowing air. The resulting mixed vapor is representative of either mixed explosive material or bulk explosives. Component materials are held in up to four individual, removable vials with vapor concentrations controlled by vial orifice size, temperature, and diluent airflow. The total concentration can be adjusted by altering vial temperature via a thermal water jacket surrounding the entirety of the device, or by adjusting the flow rate of diluent air through the device. The MV-Gen was evaluated first with surrogate compounds, followed by two types of homemade explosives, to include a binary explosive mixture and a peroxide explosive. To evaluate the device, vapors were cold-trapped on an online sampling system and analyzed by gas chromatography/mass spectrometry. It was determined that the device yielded reproducible vapor concentrations of both single and mixed components, and the ratio of these vapors can be easily adjusted to mimic varying forms of homemade explosives.