The effects of microbial degradation on ignitable liquids

Area of Science:

• Forensic Science
• Environmental Microbiology
• Organic Geochemistry

Background:

• Ignitable liquid residue identification is crucial for fire investigation.
• Microbial degradation of these residues can compromise forensic analysis.
• Evidence storage often involves extended periods at room temperature, exacerbating degradation.

Purpose of the Study:

• To evaluate the impact of microbial degradation on ignitable liquids in soil over time.
• To identify specific compound classes affected by biodegradation in fire debris.

Main Methods:

• Analysis of ignitable liquid residues in soil samples subjected to microbial degradation.
• Gas chromatography-mass spectrometry (GC-MS) for compound identification and quantification.
• Time-course evaluation of degradation patterns.

Main Results:

• Significant loss of n-alkanes (C9-C16) in gasoline and petroleum distillates.
• Branched alkanes remained largely unaffected by microbial activity.
• Monosubstituted benzenes showed substantial degradation in gasoline; even-numbered n-alkanes degraded more than odd-numbered ones in heavy distillates.

Conclusions:

• Microbial degradation significantly alters the chemical profile of ignitable liquid residues.
• Specific compound classes, like n-alkanes and monosubstituted benzenes, are vulnerable.
• Findings highlight the need for timely analysis of fire debris to mitigate evidence degradation.