Degraded Ignitable Liquids Database: An Applied Study of Weathering and Bacterial Degradation on the Chromatographic Patterns of ASTM E 1618 Ignitable Liquid Classes

 Authors: Michael E. Sigman and Mary Williams

Abstract:

Identification of ignitable liquid residues in fire debris is complicated by several factors. Background contamination from combustion of household furnishings and building materials can obscure the chromatographic pattern of an ignitable liquid. Partial evaporation (weathering) of the ignitable liquid can also lead to significant distortion of the chromatographic profile.

The purpose of this research was to address all of the problems associated with the effects of weathering and biological degradation pertaining to the process of ignitable liquid residue identification and class assignment in fire debris.

The findings from this research provide fire debris analysts hundreds of examples of weathered and biologically degraded ignitable liquid samples encompassing all ASTM E1618 classes. The resulting data records were added to the Ignitable Liquids Reference Collection (ILRC) database and linked to the record of the original sample. A “Best Practices” statement was prepared by the ILRC Committee and placed on the ILRC database website to inform forensic practice and policy in laboratories conducting fire debris analysis.

Additional work completed under this research included an investigation of the influence of weathering and biological degradation on the correct ASTM classification, and a preliminary investigation to address digital modeling of the weathering process across all ASTM classes of ignitable liquid.

The results point to a potential approach to predict weathering patterns for ignitable liquids, which will avoid the time-consuming task of weathering several ignitable liquids in search of a weathered chromatographic pattern that matches a casework sample.

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