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The effects of season and soil type on microbial degradation of gasoline residues from incendiary devices

NCJ Number
Analytical and Bioanalytical Chemistry Volume: 405 Dated: 2013 Pages: 1593-1599
Date Published
7 pages

This study examined the effects of microbial degradation of gasoline from an incendiary device over time.


The primary task of a fire debris chemist is to determine whether there is an ignitable liquid present in a fire debris sample and, if so, to classify it according to its boiling point and carbon number range; however, in organic-rich substrates such as soil, the ignitable liquid residue is subject to microbial degradation due to the ease with which bacteria can metabolize the various hydrocarbons present. This is a rapid process that is problematic in many forensic laboratories, since fire debris is often stored for extended periods of time due to case backlog. Although microbial degradation has been studied in laboratory samples, it has not been well-studied in “real-world” samples, which have not only been exposed to microbial degradation but have also suffered the effects of weathering due to the intense heat of the fire. In examining the effects of microbial degradation of gasoline from an incendiary device over time, the current study visually monitored chromatographic changes and used multivariate statistical techniques to simplify the complex data set and elucidate trends that might not otherwise be observed. Results indicated a clear difference between glass samples, which suffered the loss of low boiling compounds, and soil, which lost normal alkanes and lesser substituted aromatics. Also, devices deployed on lawn soil and in the winter season appeared to show the most extensive degradation of gasoline. Finally, although the ratio of the C3-alkylbenzenes was significantly altered in soil samples recovered from large devices, the overall chromatographic profile of gasoline recovered from smaller incendiary devices was significantly lower. 14 references (publisher abstract modified)

Date Published: January 1, 2013