How do we Identify the Chemical Composition of Improvised Explosives?
Greg W. Dicinoski, Paul R. Haddad, Emily F. Hilder, Michael C. Breadmore, Robert A. Shellie, Rosanne M. Guijt, Joseph P. Hutchinson, Cameron A. Johns, Eadaoin Tyrrell, R. Andrew Shalliker
Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Private Bag 75, Hobart 7001, Australia
Improvised explosives, are defined as explosives devices formed from commonly available ingredients such as fertilizers, have been used extensively in acts of terrorism throughout the world. Current counter-terrorism measures require rapid and reliable detection of these improvised explosives both prior to detonation (pre-blast) and after detonation (post-blast). The primary aim of pre-blast identification is to detect the explosive in situations such as airport screening, while the primary aim of post-blast identification is to determine the identity of the particular explosive used in order to assist in apprehension of the perpetrators. Both situations require reliable and rapid means of analysis using methods which can be operated by relatively unskilled personnel and in field-based locations.
In this study, capillary electrophoresis (CE) and ion chromatography (IC) have been evaluated as analytical methods for the post-and pre-blast explosive identification. A detailed survey of improvised explosives has been undertaken and a suite of 15 candidate inorganic anions and 13 candidate cations has been established for post-blast fingerprinting, and 7 candidate anions for the pre-blast scenario were selected. The separations of each of these groups of ions has been developed using IC and CE, with an emphasis on the use of instrumentation which is field-deployable or portable. To this end, miniaturised columns and robust detection methods, such as indirect spectrophotometric detection using light-emitting diode detectors have been employed. These separations have been applied to traces of the explosives and also to post-blast explosive residues and have been evaluated for their capacity to unequivocally identify the particular explosive used. The pre-blast system uses an IC instrument with reagent-free eluent generation and suppressed conductivity detection. The separation is achieved using short, self-packed columns containing Dionex AS20 stationary phase material. The short, self-packed columns allow the rapid identification of the target anions, with high speed separation being carried out in less than 3 minutes under optimised conditions.
This presentation will outline the IC and CE separation conditions, the modifications made to the instrumentation (such as the use of portable CE instrumentation) and the results obtained when using these methods for fingerprinting of explosives.