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Application of a kinetic model to predict extracted ion profiles for the identification of evaporated ignitable liquids

NCJ Number
Forensic Chemistry Volume: 24 Dated: June 2021
Briana A. Capistran ; Victoria L. McGuffin; Ruth Waddell Smith
Date Published
June 2021

In the authors previous work, accuracy in predicting total ion chromatograms (TICs) for gasoline and petroleum distillates was demonstrated, and in the current project, the model was applied for the first time to predict extracted ion profiles (EIPs) corresponding to different compound classes.


Fifteen ignitable liquids representing five classes (isoparaffinic, naphthenic-paraffinic, aromatic, petroleum distillate, and gasoline) defined in ASTM E1618 were experimentally evaporated to 50–90 percent (v/v). The kinetic model was applied to predict TICs and EIPs corresponding to the alkane, cycloalkane, aromatic, indane, and polynuclear aromatic compound classes for each evaporated liquid. Strong correlation between experimental and predicted TICs and EIPs indicated the predictive accuracy of the model. Reference collections were then generated containing predicted TICs and EIPs for each liquid corresponding to evaporation levels ranging from 10 to 90 percent. The reference collections were used to identify the ignitable liquid class in samples of increasing complexity, based on maximum correlation between the experimental and predicted chromatograms. In all cases, the correct liquid class was identified, even in the presence of substrate interferences. Overall, this work demonstrates the potential of a kinetic model to generate TICs and EIPs as a practical tool for identification of ignitable liquids in fire debris samples. (publisher abstract modified)