Comparison of Gasolines Using Gas Chromatography-Mass Spectrometry and Target Ion Response

Abstract

Gas chromatography-mass spectrometry was used to compare gasoline samples obtained from different sources based on the difference in amounts of certain components found in the headspace of gasoline using target response data. Many suspected arson cases involve comparing an ignitable liquid extracted from fire debris to a liquid found in a suspect's possession to determine if they could have had a common source. Various component ratios are proposed for determining if an unevaporated gasoline sample could have originated from the same source as an evaporated gasoline extracted from fire debris. Fifty and 75% evaporated gasoline samples were both found to contain similar ratios of certain components when compared with its unevaporated source gasoline. The results of the comparisons in this study demonstrate that for cases involving gasoline that has been evaporated up to 50% and extracted from pine, it is possible to eliminate comparison samples as originating from the same source. The results of the 75% comparisons suggest it may be possible to apply the same type of comparison to cases involving 75% evaporated gasoline.

Forensic Science

“…GC/ MS using selected ion monitoring was used to discriminate unevaporated and evaporated samples of gasoline (255,256). GC/ MS was used to compare gasoline samples obtained from different sources based on the difference in amounts of certain components found in the headspace of gasoline using target response data (257). The aromatic content in various medium-range distillate products has been determined (258).…”

Ignitable liquid identification using gas chromatography/mass spectrometry data by projected difference resolution mapping and fuzzy rule-building expert system classification

“…The initial set of target compounds were based on Dolan and coworkers [17,23]. The selection criteria were based on compounds which were found commonly in a set of 35 samples collected in the Washington, DC metropolitan area which gave consistent results with repeated injections, but showed significant differences among samples.…”

“…Particularly for gasoline, many of the major aromatic components were not included, because there is little variation between gasoline, thus these compounds were of little use for identifying samples from different sources (Dolan, personal communication, 2002). With evaporated samples, lower molecular weight components are lost first, thus ratios containing one or both components will be affected [17]. An additional compound, 2,2,4-trimethylpentane was added in this study to include a possible marker compound for octane number.…”

“…1 is a two-way GC/MS image of a gasoline sample. The target component ratio is an analysis method developed for comparing neat samples to fire debris submitted from casework [17]. The target component ratio is calculated by searching specified retention time windows for the presence of peaks of specific compounds.…”

Fire investigation and ignitable liquid residue analysis—A review: 2001–2007

“…PCA applied to GC-MS data was combined with artificial neural networks (ANN) to classify unevaporated regular and premium gasoline samples [291]. A study of 16 gasoline samples (50% evaporated), extracted from fire debris using headspace analysis, showed that all samples could be distinguished from each other based on the relative ratios of selected compounds [292]. Multiple regression coefficients were calculated for different samples of unevaporated and evaporated gasoline to determine, first, if the sample was a gasoline and, second, to discriminate between samples of gasoline [293].…”