A Survey On The Interpretive Gc Ms Analysis Of Fire Debris

The practice of arson analysis in a forensic science laboratory is based upon detecting the presence of ignitable liquids. If an ignitable liquid is present, it is suggestive of arson; if no ignitable liquid is found an arson claim is more difficult to assert. Ignitable liquids are detected using gas chromatography coupled with mass spectrometry. Instrumental results from a GC/MS can display components of an ignitable liquid but an analyst needs to make the final decision. Even with correct instrumentation and suggested guidelines, ignitable liquid analysis can be subjective and based upon the analysts' education and experience. To better understand the interpretive practices of the fire debris analysis community, a survey consisting of reference samples, mixture standards, and multiple unknowns was created in consultation with the Los Angeles Police Department Arson Unit. The samples consisted of different substrates with varying classes and volumes of ignitable liquid. They were created using a destructive distillation method first developed by the State of Florida Bureau of Forensic Fire and Explosives Analysis. Extraction of the samples was completed using a carbon strip to perform passive headspace absorption following the ASTM E 1412 method. The samples were analyzed with a GC/MS following National Commission on Forensic Science parameters. To maintain confidentiality, participant responses are stripped of identifiers and the results of the survey, details about the procedure, and discussions will be presented.