Development of a Sampling System to Stabilize Ignitable Liquid Residues in Fire Debris.

摘要

Ignitable liquid residues that are found in soils or similar materials are susceptible to microbiological attack following sample collection at a fire scene. The fact that microorganisms can metabolize components of petroleum is a well-known phenomenon to chemists responsible for analyzing fire debris. Unfortunately, the turnaround time for a fire debris case is typically more than sufficient for significant and irreversible microbial decomposition of ignitable liquid residues to occur under the right conditions. If allowed to progress unchecked, microbial degradation can eliminate the vast majority of compounds that constitute an ignitable liquid residue and ultimately lead to incorrect, inconclusive or false negative findings in fire debris cases that involve soil samples. In this work, two approaches were pursued to avoid microbial degradation of ignitable liquid residues in soil. The first was to inhibit or eliminate the microbes naturally present in soil. While some laboratories refrigerate or freeze fire debris to minimize bacterial attack, this technique is expensive, space consuming and of mixed effectiveness. We have developed a practical and effective preservative that can be used by investigators in the field to stabilize fire debris evidence. This solution consists of the anti-microbial agent triclosan, which is non-volatile and could be safely deployable by investigators. The effectiveness of triclosan has been evaluated using microbiological techniques and testing of realistic soil samples using ASTM methods verified that ignitable liquid residues can be effectively preserved for periods of up to 30 days.