Concept of pyrolysis for fire debris analysts

This paper introduces the mechanisms of pyrolysis to fire debris analysts. Pyrolysis products are produced during the combustion of substrates that are submitted to forensic laboratories for ignitable liquid residues recovery. These products, among others, create interferences and complicate the interpretation of chromatograms. Pyrolysis follows certain rules, depending mainly on the substance involved. These mechanisms are presented and illustrated with practical examples of burned substrates analyzed according to ASTM standards. Bond dissociation energies represent an important factor in the route taken by a polymer to produce pyrolysis products. These are presented, as well as the structures of some polymers commonly encountered in fire debris. The understanding of these concepts should improve the interpretation of fire debris chromatograms.