Current composition of commercially available ignitable liquids and its implications for fire debris analysis

The composition of commercially available ignitable liquids changes over time. New products are introduced onto the market, and the composition of products sold under the same name by the same manufacturer may also change. Therefore, compositional data for these liquids should be updated periodically to ensure correct interpretation of fire debris analyses. The aim of this study was to characterise ignitable liquids currently available on the Polish market and assess the implications of their composition for the detection and interpretation of residues in fire debris samples. Ignitable liquids, including gasolines, diesel fuels, solvents, and liquid barbecue firelighters, were purchased and analysed. Solid barbecue firelighters were also examined. Among the analysed solvents and thinners, the largest group consisted of products classified as "Oxygenated Solvents" according to ASTM E1618-19 (38%). The second largest group consisted of "Others-Miscellaneous" products (31%), most often composed of oxygenated and aromatic compounds. Among liquid barbecue firelighters, 82% were classified as "Oxygenated Solvents", with ethanol most commonly being the main component. Some products contained only diethylene glycol, a hygroscopic, low-volatility compound not detectable in the headspace. All gasolines showed a typical aromatic hydrocarbon profile and contained at least one oxygenated compound characteristic of gasoline: MTBE (CAS No. 1634-04-4), ETBE (CAS No. 637-92-3), or TAEE (CAS No. 919-94-8). All diesel fuels consisted of Heavy Petroleum Distillates with a typical alkane profile and contained Fatty Acid Methyl Esters (FAME) as additives. Solid barbecue firelighters most commonly contained paraffin wax or petroleum distillates.