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New Developments in SPME Part 2: Analysis of Ammonium Nitrate-based Explosives

NCJ Number
205130
Journal
Journal of Forensic Sciences Volume: 49 Issue: 2 Dated: March 2004 Pages: 215-221
Author(s)
Hayley Brown B.Sc.; K. Paul Kirkbride Ph.D.; Paul E. Pigou Ph.D.; G. Stewart Walker Ph.D.
Date Published
March 2004
Length
7 pages
Annotation
This article describes a preliminary study into the scope and limitations of on-fiber derivatization-solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) as applied to the recovery and identification of ammonium nitrate-fuel oil (ANFO)-type explosives.
Abstract
SPME and GC-MS are accepted techniques for the recovery and analysis of many types of organic explosives. These techniques, however, are not practical for the analysis of ammonium nitrate-based explosives because of the extreme polarity, low molecular weight, and high volatility of the amine moiety. As such, the authors took up an initial investigation of a derivatization process that uses alkylchloroformates to convert ammonium nitrate and methylammonium nitrate into a form that can be recovered using SPME techniques and analyzed using GC-MS techniques. The research method involved treating a solution of ammonium nitrate in water with an equal quantity of a solution of sodium hydroxide in water. The SPME fiber was immersed in this liquid for 1 minute, exposed to the headspace above any of the three derivatizing reagents for 30 seconds, and then thermally desorbed in the injection port of the GC-MS. Results indicate that the process is a simple and practical method for rendering the amine moieties present in ammonium nitrate and methylammonium nitrate amenable to SPME and GC-MS techniques for recovery and analysis of ANFO-type explosives. Additional research is being conducted on ways to decrease the detection limits, including research on the impacts of agitating the aqueous phase. Figures, references