Products of benz[a]anthracene photodegradation in the presence of known organic constituents of atmospheric aerosols

Little is known about atmospheric reaction mechanisms or products of polycyclic aromatic hydrocarbons associated with aerosol particles. Products of benz[a]anthracene photodegradation were determined after irradiation of benz[a]anthracene in the presence of three common constituents of atmospheric aerosols previously found to accelerate benz[a]anthracene photodegradation; 9,10-anthraquinone, g-xanthone, and vanillin. Irradiation was carried out in toluene, benzene, and benzene-d(6), and products were analyzed by GCMS, FTIR, and NMR. Among the major tentatively identified products were benz[a]anthracene-7,12-dione, phthalic acid, phthalic anhydride, and 1,2-benzenedicarboxaldehyde. Evidence for production of polycylic dicarboxylic acids and dialdehydes was also obtained. Product distribution was strongly influenced by solvent effects and dissolved aerosol constituents. The results suggest that products of PAH photodegradation in atmospheric aerosols are likely to be quite complex and strongly influenced by the organic composition of PAH-containing aerosol particles.