The Effects of Substrates and Elevated Temperatures on the Weathering of Ignitable Liquids

Ahna Kotula*, Caitlyn Wensel and Glen P. Jackson, Department of Forensic and Investigative Science, C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV 26506

Field (Broad Category): Forensics (Physical Sciences & Engineering) 

Student’s Major: Forensic Science 

This study aims to assist forensic investigations by providing a deeper understanding of the weathering (i.e. evaporation) of ignitable liquid residues in fire debris. Initial experiments will employ a synthetic gasoline mixture that will be evaporated to various levels at various temperature on different substrates. These weathering experiments will reveal how two major factors impact the distribution of compounds in the weathered residues: 1) the temperature at which weathering occurs, and 2) the porosity of the substrate and how the gasoline penetrates into the substrate. The study will first examine the effect of different substrates on the evaporation rates of the nine different components in the artificial gasoline. To examine how the gasoline penetrates the substrates, the experiments will be repeated with different delays between spiking and weathering the gasoline. This will be done at different temperatures/durations. The residues of the gasoline in the substrates will be collected, analyzed, and quantified using gas chromatography-mass spectrometry (GC-MS). The four substrates that will be experimented on are hard wood, soft wood, nylon carpet, and cotton because they are commonly found in fire debris. Results from weathering the gasoline without a substrate demonstrated that temperature impacts the distribution of components. We anticipate that adsorption on the surface of the substrates will not impact the relative evaporation rates of the nine compounds in the synthetic gasoline, but that absorption of gasoline into the pores of a more porous substrate would slow the evaporation of the most volatile components. 

Funding: National Institute of Justice 

Program/mechanism supporting research/creative efforts: WVU 297-level course