Classification of gel fuel by a combination of instrumental analyses

Abstract

 While kerosene and gasoline are the most common fire starters used in arson and other crimes, gel fuel is also used sporadically. In forensic science, analysis of gel fuel has been limited to the detection of methanol as the major component, and no cases of discrimination have been reported. In this study, we collected 26 gel fuel products from 13 companies and performed instrumental analyses such as headspace gas chromatography/mass spectrometry (HS-GC/MS), gas chromatography/mass spectrometry (GC/MS), and liquid chromatography/mass spectrometry (LC/MS). In addition, scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), Fourier transform infrared spectroscopy (FT-IR), and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) were also performed on the dried solids of each sample. The samples were then classified into eight groups according to the combinations of components detected by HS-GC/MS and GC/MS and dyes detected by LC/MS. Moreover, principal component analysis was conducted using pyrograms of Py-GC/MS, and amines and their pyrolytic products were used as indicators to differentiate the groups. Combining the components detected using Py-GC/MS with the SEM-EDX elemental results, it was possible to classify the same eight groups from the dried solid samples.