Measurement of C24H14 polycyclic aromatic hydrocarbons associated with a size-segregated urban aerosol

Six-ring C24H14 (MW 302) polycyclic aromatic hydrocarbons (PAH), some of which are potent mutagens, are present in urban aerosols. Size-segregated atmospheric aerosol samples from Boston, MA, were analyzed for C24H14 PAH by gas chromatography/mass spectrometry. Eleven peaks were found with mass to charge ratios of 302; of these, eight were identified using authentic standards. Five of the peaks were quantified. For ea ch of these five, the distributions with respect to particle size were bimodal with the majority of the mass associated with accumulation mode particles (0.3-1.0 mu m) and a smaller fraction of the mass associated with ultrafine mode particles (0.09-0.14 mu m). These distributions are similar to those observed for PAH of molecular weight 252-278 in the same sample but different from those of benzo[ghi]perylene (MW 276) and coronene (MW 300), which were associated to a greater degree with ultrafine particles. The data suggest that C24H14 PAH repartition to larger particles by vaporization and sorption more rapidly than do benzo[ghi]perylene and coronene. The total concentration of C24H14 PAH (1.5 ng/m(3)) was comparable to that of benzo[a]pyrene in the same sample. Because of their mutagenicities, C24H14 PAH may make a contribution to the genotoxicity of urban aerosols comparable to that of benzo[a]pyrene.