Volume 44, Issue 3 (May 1999)
A Comprehensive Sample Preparation Scheme for Accelerants in Suspect Arson Cases
This study represents a critical comparison of adsorbent based heated headspace methods for the enrichment of volatiles from fire debris. A dynamic and a static method, based on charcoal adsorption and solvent extraction are compared to the solid phase micro extraction (SPME) procedure. The SPME method has been optimized in respect to fiber type, sampling time, sampling temperature, analyte concentration and the effects of water. Collection efficiencies were evaluated for a variety of accelerant types, ranging from methanol to diesel fuel. The minimum detectable quantity for each of the methods is within an order of magnitude for most accelerant types. We propose a two step method based on SPME with two different fibers. Polar and water soluble accelerants such as ethanol and light petroleum distillates are most effectively enriched at low temperature on Carboxen™, a newly developed high capacity fiber which contains a carbon based adsorbent. Low volatility accelerants such as diesel fuel can be recovered on a methylpolysiloxane type fiber at elevated temperature. Limitations of currently used sample preparation methods are discussed.