Detection of gasoline on suspects’ shoes using the technique of Headspace - Gas Chromatography – Mass Spectrometry (HS-GC-MS)

Abstract

This study aimed to investigate the persistence of gasoline residues on six types of shoe sole materials, including natural rubber, synthetic rubber, ethylene-vinyl acetate (EVA), polyurethane (PU), nylon, and polyvinyl chloride (PVC). Volunteers wore shoes made with each sole type and stepped onto ceramic tiles containing 100 µL of gasoline droplets. Samples of gasoline residues were collected from the soles at 0, 3, and 6 hours after contact using activated carbon enclosed in tea bags. The collected samples were analyzed for gasoline components using Headspace Gas Chromatography-Mass Spectrometry (HS-GC-MS). The analysis found that at 0 hr. all six samples of shoe sole materials were detected the presence of gasoline components in 12 peaks, at 3 hr. four samples of shoe sole materials were detected the presence of gasoline components in 12 peaks, and at 6 hr, only synthetic rubber and phylon were detected the presence of gasolene components in 12 peaks.  The results also showed that gasoline residues remained on the shoe soles even after 6 hours of stepping on the tile, evidenced by the decrease in both the number of peaks and the area under the peaks in the chromatogram. This method could be applied in forensic science to detect gasoline residues on footwear and help link the perpetrator to the crime scene.