Gas Chromatography – Flame Ionization Detector (GC-FID) Identification of gasoline on arson suspects’ shoes by the technique of Gas Chromatography-Flame Ionization Detector

Abstract

Arson fire is one of the most dangerous crime that is difficult to investigate. Detection of gasoline residue can provide important information to link evidence with an arson suspect. The objective of this project was to study the application of chromatography-flame ionization detector technique (GC-FID) to the detection of gasoline vapor on suspect’s sneaker sole. In this work, 100 μl of gasoline liquid was dropped on the soil surface, concrete and tile floors. Samples were taken from sneakers that were worn by a volunteer and stepped on the substrates for 30 seconds. The sample of gasoline vapor was collected by using activated carbon packed in a tea bag. The samples were taken immediately and at 1 h., 3 h., 6 h, 12 h. 16 h., and 24 h. after stepping on the substrates. The peaks of benzene, toluene, o-xylene, p-xylene and ethyltoluene in the chromatogram of the sample were used to identify the gasoline. The gasoline vapor was detected in all samples even in the samples taken 24 h. (8.06-8.48 ppm) after the deposition of gasoline liquid. For the samples collected immediately after gasoline deposition, the higher amount of the gasoline vapor was found in the tile-floor sample (30.11 ppm) compared to that in the soil-surface sample (12.83 ppm). Moreover, a sharp drop in the amount of gasoline was observed in all samples collected at a longer period than one hour after the deposition of gasoline. However, the gasoline content remained constant (approximately 8-10 ppm) in all samples collected at 6 h. to 24 h. after gasoline deposition. The results obtained demonstrate the potential of this methodology to help in detection of gasoline on the suspect’s sneaker in arson cases.