These days gas chromatography (GC) is one of the primary analytical techniques used in every forensic laboratory. GC is widely used by forensic scientists - from analysis of body fluids for the presence of illegal substances, to testing of fiber and blood from a crime scene, and to detect residue from explosives. Yet scientists from Ohio University explored another application of gas chromatography with differential mobility spectrometry as a low cost, onsite detection method for ignitable liquids.

According to the US Fire Administration, arson is the leading cause of fires and the second leading cause of deaths and injures, and that’s why arson investigation is of forensic significance for the criminal justice system.

Commercially available fuels or solvents that are mixtures consisting of hundreds of components are typically used to start a fire. Analysis becomes very difficult because ignitable liquids consist of same or similar components at different concentrations, in addition, fire may evaporate some of the components and thus altering the composition of residual ignitable liquids found in fire debris.

Gas chromatography - mass spectrometry (GC/MS) is a well established method for analysis of ignitable liquids; however, Yao Lu and Peter B. Harrington proposed a gas chromatography / differential mobility spectrometry (GC-DMS) method. The duo tested a variety of commercially available petroleum-based ignitable liquids and showed that two-way GC-DMS data provides more information for classification and better prediction results than either chromatograms or DMS spectra.

References: “Forensic Application of Gas Chromatography-Differential Mobility Spectrometry with Two-Way Classification of Ignitable Liquids from Fire Debris”, Yao Lu and Peter B. Harrington, Analytical Chemistry, 2007, DOI:10.1021/ac0707028

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