Influence of Placement Time on Identification of Combustion Residues of Alkyd Paint Thinners

To probe into the changes of characteristic components of combustion residues from alkyd paint thinners under different durations of placement. The alkyd paint thinner (X-6), selected as the research object, was imbibed into absorbent cottons (as the carrier) that were afterwards ignited and burnt for certain durations before extinguishment, having such resultant combustion residues left and stored for 0, 3, 5, 7 and 9 days, respectively. GC-MS was to analyze the variation of characteristic components of the combustion residues under different durations of storage. The original sampling alkyd paint thinner mainly contains aromatic hydrocarbons and alkanes. Alkanes were found of no appearance in the combustion residues while new substances, e.g., thick cyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and ninhydrin, were detected within 5 days, yet PAHs were unable to be detected after 7 days and ethyl benzene was the only left one of aromatic hydrocarbons after 9 days. Thus, the list of target compounds allowed inclusion of tritoluene, phenanthrene, fluoranthene and pyrene. Both tritoluene and indene were revealed of their contents not affected with the storage time, whereas polycyclic aromatic hydrocarbons even increased their contents. For actual fire investigation and identification of the related material evidence, the alkyd paint thinner should be detected within 5 days, and timely extracted and delivered for examination.