Determination of polycyclic aromatic compounds and dioxin receptor ligands present in diesel exhaust particulate extracts

Polycyclic aromatic compounds and dioxin receptor ligands present in diesel particulate extract fractions and subfractions were determined. A crude model diesel particulate extract was fractionated into five fractions (I-V), fractions I, II and III were further fractionated into subfractions (I-1, I-2, II-1 to II-7 and III-1 to III-6). The amounts of 33 PAC present in fraction II and its subfractions were determined by gas chromatography-mass spectrometry. The amounts of 1-nitropyrene present in fraction III and its subfractions were analysed by high performance liquid chromatography with fluorescence detection. The ability of each fraction and subfraction to compete with 2,3,7,8-tetrachloro[1,6-[H-3]]dibenzo-p-dioxin for specific binding to its receptor was determined. The major recovery of dioxin receptor binding activity was present in fraction III and on subfractionation this activity coeluted with 1-nitropyrene. In light of the low binding activity of 1-nitropyrene, these data indicate that the compounds responsible for the high binding activity associated with fraction III, remain to be characterised. Among the subfractions, II-4, which contained the second largest amount of PAC, displayed the highest dioxin receptor binding activity. Principal components analysis showed that dioxin receptor binding activity is correlated with PAC content and that benzo(a)anthracene, chrysene and benzo(a)pyrene play an important role in the observed dioxin receptor binding. Copyright (C) 1996 Elsevier Science Ltd