Biologically-Directed Fractionation of Four Seasonal Extracts of Airborne Particulates and Related Chemical Studies

Ames assays (TA98) were applied toward assessing the mutagenic activities of extract fractions and subfractions of inhalable airborne particulate matter obtained in the manner of the earlier ATEOS study. Specifically, sequential cyclohexane, dichloromethane and acetone extracts of 24-hour samples were composited on a quarterly basis (ca 15 samples/quarter) and then fractionated using thin layer chromatography. For all four quarters the highest specific activities were associated with dichloromethane extracts and, specifically, its most polar fractions. Hydroxynitro-PAH are likely components in the dichloromethane extract. The cyclohexane extracts, containing PAH and nitro-PAH, were much less active. The acetone extracts had significant activity possibly associated with azaarenes and phenols. While PAH levels decreased in summer, nitro-PAH levels rose. No simple trend was observed for the PAH-quinones. 2-Nitropyren-1-ol, formed readily via solution photoxidation of 1-nitropyrene, does not appear to be formed under ambient atmospheric conditions. Preliminary FTIR, HPTLC and GC/MS results are described.