Identification and quantification of ozonation products of anthracene and phenanthrene adsorbed on silica particles

Primary products of the reactions of gas-phase ozone with anthracene and phenanthrene adsorbed on silica model particles have been investigated. Silica was selected as proxy for mineral atmospheric particles. The particles, coated with anthracene or phenanthrene and placed on a filter, were exposed in a reaction cell to a gaseous ozone flow. Ozone concentration was constant ((6.0±0.6)×1013 molecule cm−3) during the experiments. Anthracene, phenanthrene and their ozonation products were then extracted by focused microwave-assisted extraction or fluid pressurized extraction and analyzed by gas chromatography coupled to mass spectrometry. Anthraquinone and anthrone on the one hand, and 1,1′-biphenyl-2,2′-dicarboxaldehyde on the other hand were identified as the products of anthracene and phenanthrene, respectively and quantified versus time of ozone exposure. This kinetical approach allowed to show that anthraquinone, anthrone and 1,1′-biphenyl-2,2′-dicarboxaldehyde are the primary products of the studied reactions, and to determine their formation yields (respectively, 0.42±0.04, 0.056±0.005 and 1.0±0.4).