DISTRIBUTION OF BENZO[A]PYRENE AND CORONENE WITH RESPECT TO PARTICLE-SIZE IN PASADENA AEROSOLS IN THE SUB-MICRON RANGE

Two polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene (BaP) and coronene (COR) were studied. Although reported equilibrium vapor concentrations of BaP are much higher than atmospheric concentrations, detectable amounts of BaP were not found in the gas phase. Coronene vapor pressures are too low for this species to appear in the gas phase. Aerosols were size fractionated by an eight stage low pressure impactor capable of size fractionation down to 0.05 μm dia. After ultrasonic extraction with benzene, each stage of the impactor was analyzed for BaP and COR by thin layer Chromatographie and spectrophotofluorometric (TLC-SPF) analysis. About 75% of the BaP and 85% of the COR are associated with particles of aerodynamic diameter less than 0.26 μn. Almost one half of the total mass of both PAHs is associated with aerosols in a very narrow size range (0.075-0.12 μm). Total concentrations ranged between 0.39 and 1.06 ng m-3 for BaP and between 1.81 and 6.66 ng m-3 for COR. The distributions of both PAHs with respect to particle size were unimodal. © 1978.