Flammable liquids in non-flammable products as potential interferences in the determination of ignitable liquid residues in fire debris

The clothing of suspected arsonists is often analyzed for the presence of ignitable liquids. Personal care products (PCPs) are ubiquitous in our society and can contaminate clothing, so their potential interference is an important consideration in the interpretation of casework samples. Thirty-two samples of various hygiene products and hand cleaners were analyzed using headspace concentration-gas chromatography/mass spectrometry (GC/MS). Despite occasionally containing one or two hydrocarbon compounds found in ignitable liquids, all the antiperspirants and deodorants were readily distinguished from ignitable liquids because they lacked any of the key diagnostic features of ignitable liquids in their extracted ion profiles (EIPs). Two samples labeled as hand cleaners displayed characteristic patterns of heavy petroleum distillates, which, if found on a suspect’s clothing, could cause the misleading assumption that the source of the liquid was flammable. However, the petroleum distillates in these two hand-cleaning products were not flammable, according to both their packaging and safety data sheets, because they were formulated as emulsions with water. This study also includes a casework example of a heavy petroleum distillate in a fire debris sample. However, the co-presence of abundant fatty acid methyl esters increased the probability that the original source was either a biodiesel blend or a non-flammable formulation product and therefore raises reasonable doubt about the flammability of the original product. The results of this work are limited by the GC/MS method, which could not detect volatiles like acetone, propanol, and ethanol eluting before a retention index of 700 nor non-volatile emulsifiers/surfactants.