Separation and identification of polar degradation products of benzo[a]pyrene with ozone by atmospheric pressure chemical ionization-mass spectrometry after optimized column chromatographic clean-up

The environmental relevance of oxidized degradation products of polycyclic aromatic hydrocarbons (PAHs) increases due to enhanced combustion of organi c matter and fossil fuels. For PAHs consisting of more than three condensed aromatic rings, soot aerosols are the main carrier, on the surface of whic h they can react with trace gases like ozone. In this study the clean-up pr ocedure and analysis of ozonized benzo[a]pyrene (B[a]P) was optimized. B[a] P and its degradation products were preseparated into three fractions. Diff erent reversed-phase materials were evaluated for high-performance liquid c hromatographic separation. Among these, a phenyl-modified silica material p roved best-suited and the chromatographic separation was optimized on this material. For the detection of separated degradation products, liquid chrom atography-atmospheric pressure chemical ionization-mass spectrometry (LC-AP CI-MS) was used. With this method, 29 components could be characterized. Be sides the three known main degradation products (B[a]P-1,6-dione, B[a]P-3,6 -dione, B[a]P-6,12-dione, B[a]P-4,5-dione and 4-oxa-benzo[d,e,f,]chrysene-5 -one (B[def]C-lactone), were identified for the first time with the help of reference substances. B[def]C-lactone is known as a substance with a mutag enic potential similar to B[a]P. Several other compounds could be tentative ly identified. (C) 1999 Elsevier Science B.V. All rights reserved.