FORMATION OF OXYGENATED-POLYCYCLIC AROMATIC COMPOUNDS IN AEROSOL FROM THE PHOTO-OXIDATION OFo-TOLUALDEHYDE

The secondary organic aerosol formed during the photo-oxidation of o-tolualdehyde in a large smog reaction chamber has been studied using comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry. The separation and detection system was coupled directly to an aerosol thermal desorption stage, providing the ability to resolve all gas chromatography amenable species in a single experimental procedure. The organic content of aerosol formed from the photo-oxidation of o-tolualdehyde contained a diverse range of chemical functionalities including mono-aromatic, carboxylic acid and carbonyl which were predicted as photochemical by-products by a comprehensive chemical mechanism. Around 3% of the organic aerosol content resolved was polycyclic-aromatic in nature. This has indicated that the formation of relatively low volatility by-products was possible via the ring-retained channel from a mono-aromatic precursor. Species found included 2,3 naphthalene dicarboxylic acid, and anthraquinone quantitatively accounting for 0.40% (24.78 ng) and 0.075% (4.64 ng) respectively of the total aerosol (6181.4 ng).