Explosive and Taggant Detection with Ionscan

Abstract

A study of a number of commercial explosives and proposed taggants was performed with a commercially available Ion Mobility Spectrometer (IMS), IONSCAN, manufactured by Barringer for detection of explosives and drugs. The ion-molecule chemistry, i.e. the type of ions formed in the ionization chamber, and the stability of the formed ions when subjected to the IMS detector environment are affected by several IMS operating conditions. The operating temperature and the reactant ion are the two dominant factors in dictating which particular ions are detected from a molecular species introduced in a vapor (or gaseous) form into the reaction region. For a low false alarm it is desireable to select operating conditions in such a way that multiple ions are formed from the same molecular species. Ion identification under different operating temperatures and reactant ions for many explosives of interest and taggants proposed by ICAO are reported in this paper. Results of laboratory and field tests of false alarm rate (FAR) are reported for both discrete and continuous modes of operation of IONSCAN. Different sampling techniques for volatiles such as the International Civil Aviation Organization (ICAO) taggants and non-volatile explosives or explosives-related substances are discussed. Advantages and/or disadvantages are evaluated for each type of sampling technique.