Overcoming challenges in fire debris analysis caused by evaporation

The comparison of chromatograms from fire debris and known ignitable liquid reference collections is complicated by the evaporation of the ignitable liquids during a fire, which causes chemical changes in the evaporated liquids. Although forensic laboratories include evaporated standards in their reference collections of ignitable liquids and there has been an increasing interest in the study of evaporation, there is currently no standardized method for evaporating ignitable liquids. This research investigated different factors that affect evaporation and the application of a mathematical model to fire debris analysis.;Gasoline was evaporated under different agitation conditions and in vessels with different surface areas to determine the effect of these parameters on the evaporation process. Fraction remaining plots were generated for several characteristic compounds in gasoline with a range of volatility to assess the reproducibility associated with the different factors. Ultimately, agitation was determined to generate the most reproducible data.;A previously developed mathematical model was used with three petroleum distillates and gasoline to generate theoretical chromatograms of the evaporated liquids. Pearson product-moment correlation (PPMC) coefficients were used to assess the correlation between the theoretical and experimental chromatograms. Strong correlation was observed for all three petroleum distillates, while the model showed potential for predicting the evaporation of gasoline as well.