Polynuclear aromatic hydrocarbons in diesel emission particulates

A preliminary characterization of polynuclear aromatic hydrocarbons (PAH) in dichloromethane extracts of diesel exhaust particulates is described. Acid-base liquid-liquid partitioning followed by adsorption chromatography was used to isolate the PAH fraction. Compounds were identified primarily by the mass spectra of high-resolution gas chromatographic effluents. Three four-ring PAHs and their alkyl-substituted homologues were the predominant constituents. In addition, ultraviolet spectra of four high performance liquid chromatography-separated PAHs were superimposable with those of reference compounds leading to their unambiguous identification. These results show the advantage of using several complementary techniques for characterization rather than gas chromatrographapy-mass spectrometry alone.