A Comprehensive Study of the Alteration of Ignitable Liquids by Weathering and Microbial Degradation.

The differing effects of weathering and microbial degradation are described here in a comprehensive study that involved 50 different ignitable liquids from the Ignitable Liquids Database and Reference Collection. Examples of ignitable liquid residues from each of the main classes established by the American Society of Testing and Materials are presented. Weathering was accomplished via evaporation, whereas microbial degradation was carried out on soil at room temperature for periods of up to 21 days.

Preserving ignitable liquid residues on soil using Triclosan as an anti-microbial agent.

When a fire is suspected to be intentionally set, fire debris samples can be collected and analyzed for ignitable liquid residues (ILRs). In some cases, samples will contain highly organic substrates such as soil or rotting wood. These substrates will contain a high bacterial load, which can result in systematic and irreversible damage to the ILR due to microbial degradation.

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

The primary task of a fire debris chemist is to determine if 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 which is problematic in many forensic laboratories as fire debris is often stored for extended periods of time due to case backlog.

Comparing the effects of weathering and microbial degradation on gasoline using principal components analysis.

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.

The effect of microbial degradation on the chromatographic profiles of tiki torch fuel, lamp oil, and turpentine.

Biodegradation can result in selective removal of many of the compounds required for the identification of an ignitable liquid. In this study, the effects of microbial degradation on tiki torch fuel, lamp oil, and turpentine are reported. Samples of soil spiked with 20 μL of the liquids were stored at room temperature for up to 7 days.

The effects of microbial degradation on ignitable liquids.

The identification of ignitable liquid residues in fire debris is a key finding for determining the cause and origin of a suspicious fire. However, the complex mixtures of organic compounds that comprise ignitable liquids are susceptible to microbiological attack following collection of the sample. Biodegradation can result in selective removal of many of the compounds required for identification of an ignitable liquid.