GC/MS data from fire debris samples: Interpretation and applications

Mass chromatography is currently being adapted by many forensic laboratories as the preferred approach for interpreting GC/MS data from fire debris samples. This paper first describes software approaches for minimizing interferences and for facilitating the identification of petroleum liquids when using this approach. Next, guidelines are developed for recognizing chromatographic distortion that often occurs when petroleum liquids are recovered using the popular solid adsorption/elution method. It is seen that for a given petroleum liquid, paraffinic:aromatic ratios can vary eight fold depending on the recovery conditions and sample concentration. Finally, the application of these software tools and guidelines to case samples is illustrated, and an approach for categorizing an exemplar collection on the basis of qualitative features and peak height ratios is demonstrated.