Classification of Weathered Kerosene and Diesel Fuel using Passive Headspace Concentration with Activated Charcoal Strip and Statistical Analysis Technique

Abstract

Ignitable liquids are present in trace amounts in samples collected from arson scenes therefore their chemical composition often differs from their original composition. This is due to partial evaporation, burning and contamination by pyrolysis products at the scenes. The research was done using two techniques, passive headspace concentration with activated charcoal strip and statistical Analysis, to classify weathered kerosene and diesel fuel. The passive headspace used GC-FID chromatogram pattern to visually identify both weathered ignitable liquids while statistical analysis used cluster formation to group them based on unique characteristics of their hydrocarbons and materials used in the samples. Four case studies were done which consisted of forty-two experiments carried out on twenty-six weathered and unweathered samples that were analyzed under various conditions which included various time of burning, weathering and oven temperature. The Petroleum based ignitable liquids, kerosene and diesel, were used on different types of materials for analysis under various atmospheric conditions. The result showed visual distinction between weathered kerosene and diesel fuel at the initial stage of weathering but it was more difficult to distinguish as samples became weathered over time. Hence, this is one of the reasons why the chromatogram alone cannot be used to visually distinguish between these weathered samples. Therefore, the combination of the chromatographic pattern and statistical method were applied in this research. It was possible to distinguish between the weathered kerosene and diesel fuel using statistical analysis based on n-alkane data derived from Gas Chromatography- Flame Ionization Detector (GC-FID) method.