Application of head-space analysis with passive adsorption for forensic purposes in the automated thermal desorption-gas chromatography-mass spectrometry system

Offenders often use petroleum products as accelerants to commit an arson. A multi-component mixture of organic compounds isolated from the fire debris significantly differs from the initial one. These changes result from many factors, i.e. evaporation of the volatile components or presence of some organic compounds in the sample, which do not originate from the petroleum product (e.g. extinguishing medium components, products of pyrolysis of the burned material). The aim of presented research was to evaluate the influence of these factors. A series of experiments were carried out, and the analytical procedure was worked out. The headspace analysis with passive adsorption or the liquid extraction with ultrasonification was used for separation and concentration of the analytes. The mixture of organic compounds (accelerants, pollutants) was identified by the use of gas chromatography hyphenated with mass spectrometry. Principal component analysis (PCA) and likelihood ratio approach (LR) were applied to distinguish between evaporated samples of kerosene and diesel fuel. The elaborated procedure was verified both, witch inter-laboratory tests and using it for examinations of simulated fire debris.