MOLECULAR SPECIATION OF SECONDARY ORGANIC AEROSOL FROM PHOTOOXIDATIONOF THE HIGHER ALKENES - 1-OCTENE AND 1-DECENE

Outdoor smog chamber photooxidations to determine the molecular compos ition of secondary organic aerosol(SOA) from 1-octene and 1-decene in sunlight-irradiated hydrocarbon-NOx mixtures are reported. The observe d products are consistent with the current understanding of alkene rea ctions with OH and O-3. Gas-phase mechanisms leading to the observed p roducts are outlined. Heptanal, heptanoic acid, and dihydro-5-propyl-2 (3H)-furanone were the dominant organics identified in 1-octene aeroso l. The corresponding species in 1-decene aerosol were nonanal, nonanoi c acid, and dihydro-5-pentyl-2(3H)-furanone. Measured aerosol yields f rom 1-octene and 1-decene experiments are also reported, and are found to correlate with organic mass concentration according to semi-volati le gas/particle partitioning theory. A new organic aerosol extraction procedure utilizing supercritical CO2 extraction is outlined. (C) 1997 Elsevier Science Ltd.