Forensic analysis of biodiesel

•An analysis of several different biodiesel blends has been performed.•Distinction between blends is made via the abundances of fatty acid methyl esters.•Biodiesel blends are subject to microbial degradation to a large extent.•Biodiesel is resistant to evaporation, but degrades on heating in air.

The analysis of four different biodiesel blends, as well as homemade biodiesel prepared from vegetable oil, has been performed using gas chromatography-mass spectrometry. The identification of methyl esters within the biodiesel along with any background components is made possible by recognizing their mass spectral fragmentation patterns. These fuels were subjected to typical fire scene environments, specifically weathering and microbial degradation, to investigate how these environments affect the analysis. A matrix study was also performed on wood, carpet, and clothing in order to identify any interferences from these substrates. The data obtained herein will provide the forensic science community with the data needed to help recognize these increasingly common ignitable liquids.