Accelerant Identification in Fire Debris by TCT GC MS

The chemical detection of ignitable fuel traces in fire debris is a challenge requiring highly sensitive, hyphenated analytical systems. One coupled system suitable for the task is thermal desorption cold trap injection–gas chromatography–mass spectrometry (TCT–GC–MS). In this study, thermal desorption and cryogenic trapping were optimized to eliminate matrix interferences and to enrich target compounds in fire debris. Subsequent GC–MS provided chromatographic profiles of target ionic species required for the unequivocal identification of accelerants.

Introduction The chemical analysis of fire debris for traces of ignitable fuels is both problematic and complex.1–9 Arson investigators have proposed various solutions based on identification of the accelerant,3,10 matrix effects,11,12 interferences of pyrolytic products,13,14 a comparison with inadequate standard chromatograms,15,16 the low content of target compounds, the tedious preliminary sample manipulation17 and the timedependant modification of the accelerant chromatographic profile.18

Many extraction techniques have been used to minimize the negative effects mentioned above, including passive adsorption/thermal desorption and solvent extraction,17 headspace19 and solid-phase micro-extraction.All of these extraction techniques when coupled with gas chromatography (GC)–mass spectrometry (MS) give results that, in the majority of instances, are sufficient to identify the original accelerant. Further improvements applied to certain method phases or components increase the performance of the method.

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