Identify Residual Gasoline Components in Combustion Residues in Arson Site with ATD-GC-MS

A method was developed for the analysis of the components of combustion residues in arson site by ATD-GC-MS, in order to determine the presence of gasoline components with target compound method. The combustion test was made on 92^# gasoline standard, the 25 common blank samples and blank spiked samples (all solid wood floor, alarm clock shell, folder, ordinary cotton wadding and plastic washbasin). The combustion residue obtained was adsorbed by Tenax TA adsorption tube and desorbed by second-order desorption mode, and then separated and identified by GC-MS. The category and relative aboundance of the 4 classes composed of compound (alkanes m/z 57, 85, aromatics m/z 91, 105, 119, indene and naphthalene m/z 117, 131 and naphthalene m/z 128, 142, 156) in combustion residues of the sample in the TIC chromatogram were compared with those of combustion residues of gasoline standard and blank sample by the target compound method, thus to determine whether there was gasoline in the sample. The results showed that:A combustion law was presented after combustion of gasoline that the relative abundance of light components decreased, the relative abundance of heavy components increased, and the retention time moved backward; the same components could be detected in blank samples after combustion, but the category and relative abundance of components were different from those of combustion residues of gasoline standard; gasoline components were detected in combustion residues of spiked blank samples, and their relative abundance and combustion law were consistent with those of combustion residues of gasoline standard.