Faced with a growing number of ignitable chemicals with similar characteristics, arson investigators have their hands full trying to tell residues of insecticide, for example, from those of gasoline. But identifying fuels used to set fires will be easier now, thanks to some help from the National Institute of Standards and Technology (NIST).
Law enforcement agencies, insurance fraud investigators and forensic services are expected to use Standard Reference Material (SRM) 2285, NIST's first standard intended to aid arson investigations. The new SRM is a liquid containing 15 compounds from common accelerants in various certified concentrations. It will be used to calibrate instruments that help analysts classify fire scene residues into six categories of fuels.
The hydrocarbon compounds are separated and identified based on how long it takes for them to pass through an instrument called a gas chromatograph. The retention time depends partly on a compound's volatility, or how fast it changes from liquid to vapor, and partly on experimental conditions such as temperature. Users analyze the SRM, analyze the residue from the crime scene and compare the retention time patterns to help identify the components used at the fire.
The instruments' readouts indicate both the presence and concentration of the various components; these patterns may indicate a particular fuel source. In helping investigators accurately identify the components and thus the original fuel used to set a fire, the SRM may help improve the 2 percent national conviction rate for arson cases. SRM 2285 also may be useful in the petroleum industry and environmental science.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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