Ethylene combustion products from a jet-stirred/plug-flow reactor were characterized by gas chromatography/mass spectrometry, gas chromatography/Fourier transform infrared spectrometry, and high-performance liquid chromatography with UV spectrophotometric detection. Samples were also tested for mutagenicity both in the presence and in the absence of an exogenous metabolizing enzyme system (PMS) using a forward mutation assay based on Salmonella typhimurium. By correlating chemical analysis findings with PMS-dependent (+PMS) mutagenicity data, it was determined that cyclopenta[cd]pyrene (CPP) and fluoranthene (FLA) accounted for the bulk of the mutagenicity at high dose levels (300 μg/mL). However, at low dose (30 μg/mL) the observed mutagenicity of the sample was from 1.5 to 7 times greater than the sum of the mutagenic contributions of known components. HPLC fractionation and bioassay results showed that a fraction composed mainly of CPP was responsible for 50% of the +PMS mutagenicity of the plug-flow sample while a second fraction containing FLA accounted for an additional 8%. However, three other mutagenic fractions were also obtained and were found to be composed of C20–C30 (five to nine fused rings) polycyclic aromatic hydrocarbons (PAH). Together these three fractions accounted for 42% of the total +PMS activity. Nine ethynyl-substituted aromatics were identified including three ethynyl-acenaphthylene isomers, one of which was among the 10 most abundant species. Also, nitrogen-containing organics were detected at trace levels by GC with nitrogen-specific detection. © 1990, American Chemical Society. All rights reserved.
