Detection of Volatile Vapors Emitted from Explosives with a Handheld Ion Mobility Spectrometer

Vapor detection of plastic explosives is difficult because of the low vapor pressures of explosive components (i.e. RDX and PETN) present in the complex elastomeric matrix. To facilitate vapor detection of plastic explosives, detection agents (taggants) with higher vapor pressures can be added to bulk explosives during manufacture. This paper investigates the detection of two of these taggants, ethyleneglycol dinitrate (EGDN) and 2,3-dimethyl-2,3-dinitrobutane (DMNB), using a handheld ion mobility spectrometer. These two taggants were detected both from neat vapor sources as well as from bulk explosives (nitroglycerin (NG)-dynamite and C-4 tagged with DMNB). EGDN was detected from NG-dynamite as EGDN·NO₃^- at a reduced mobility value of 1.45 cm² V^-1 s^-1 with detection limits estimated to be about 10 ppb_v. DMNB was identified from tagged C-4 as both negative and positive ions with reduced mobility values of 1.33 cm² V^-1 s^-1 for DMNB·NO₂^- and 1.44 cm² V^-1 s^-1 for DMNB·NH₄⁺. Positive ions for cyclohexanone were also apparent in the spectra from tagged C-4 producing three additional peaks.