The use of chemical composition and additives to classify petrol and diesel using gas chromatography-mass spectrometry and chemometric analysis: a UK study

The identification of the fuel found in a crime scene and establishing its source is important for forensic investigations. In this study petrol and diesel samples were analysed in order to identify chemical composition and additives with the aim of obtaining a set of markers or compounds that will allow forensic scientists to identify fuel sources. The study was performed using petrol and diesel sold in the city of Lincoln (UK) during four seasons (winter, spring, summer, autumn).Diesel samples, representing eight different brands were analyzed by gas chromatography?mass spectrometry (GC?MS) and principal component analysis (PCA). From the GC–MS analytical results, MTBE and ETBE were identified as the additive more preferably added in super unleaded petrol samples that can be used to aid in separation and identification. In diesel, the distribution of FAME contents showed the effect of seasonal variation as these were found in all spring, summer and autumn samples, but not found in all winter ones. The selection of a reduced number of key fuel compounds and additives was also shown to be sufficient to achieve a high level of classification among the different fuel samples. Leave–one–out cross–validation was applied in order to validate the results.