Study of chemical modifications in acidified ignitable liquids analysed by GC–MS

• The chemical modifications of acidified gasoline and diesel fuel were studied.
• Considerable qualitative and semi-quantitative changes were observed in the chromatographic profiles.
• The acidification of ignitable liquids can be considered as new distortion effect.
• Some recommendations to identify acidified gasoline and diesel fuel are proposed.

In this work, mixtures of gasoline with sulphuric acid and diesel fuel with sulphuric acid were analysed by gas chromatography–mass spectrometry (GC–MS). The results showed considerable qualitative and semi-quantitative modifications in the chromatographic profiles of the ignitable liquids (ILs). In the case of acidified gasoline, the alteration of the abundances of aromatic compounds and the hydrolysis of an oxygenated compound such as methyl tert-butyl ether (MTBE), in addition to the immediate and unexpected appearance of tert-butylated compounds were observed. In the case of acidified diesel fuel, the alteration of aromatic compounds occurred. These sequential changes were then studied in detail in order to explain the chemical modifications taking place. These extensive chemical modifications may be considered as a new chromatographic profile distortion effect, the acidification of ILs. As such modifications are not generally taken into account in the criteria followed to assess the classification of an IL, we propose some recommendations helping to the identification of acidified ILs. This information can be especially useful to detect and identify non-burned ILs from seized or failed improvised incendiary devices made with mixtures of sulphuric acid–IL, or ILs altered intentionally with the aim to modify their composition.