Comparing the Effects of Weathering and Microbial Degradation on Gasoline Using Principal Components Analysis

Authors

  • Dee A. Turner B.S.,

    1. Department of Chemistry and Chemical Biology, Forensic and Investigative Sciences Program, Indiana University Purdue University Indianapolis (IUPUI), 402 North Blackford Street, LD 326, Indianapolis, IN 46202.
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  • John V. Goodpaster Ph.D.

    1. Department of Chemistry and Chemical Biology, Forensic and Investigative Sciences Program, Indiana University Purdue University Indianapolis (IUPUI), 402 North Blackford Street, LD 326, Indianapolis, IN 46202.
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  • Financial support provided by the National Science Foundation via a GK-12 Fellowship.

Additional information and reprint requests:
John V. Goodpaster, Ph.D.
Department of Chemistry and Chemical Biology
Forensic and Investigative Sciences Program
Indiana University Purdue University Indianapolis (IUPUI)
402 North Blackford Street, LD 326
Indianapolis, IN 46202
E-mail: jvgoodpa@iupui.edu

Abstract

Abstract:  Ignitable liquid residues recovered from a fire scene will often show signs of weathering as a result of exposure to the heat of the fire. In addition, when the substrate is rich in organic matter, both weathering and microbial degradation may be observed. In this study, 20 μL aliquots of fresh gasoline samples were intentionally weathered and also subjected to microbial degradation in potting soil. These samples were then analyzed using a passive adsorption–elution recovery method and gas chromatography/mass spectrometry. Peak areas from compounds of interest were normalized and autoscaled and then subjected to principal components analysis. This analysis showed that while lower boiling compounds are subject to weathering, a different set of compounds are subject to microbial degradation. Of the compounds studied, heptane, octane, toluene, and ethylbenzene were the most vulnerable to both weathering and microbial degradation. In contrast, 1,3,5-trimethylbenzene and 2-ethyltoluene were the most resistant to both phenomena.

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