Structural characteristics of polycyclic aromatic hydrocarbon isomers in coal tars and combustion products.

4 Isomeric polycyclic aromatic hydrocarbons (PAH) with two to six rings in coal-derived products and in a carbon black were separated, identified, and quantified by using capillary column gas chromatography and gas chromatography-mass spectrometry. A newly synthesized smectic liquid-crystalline polysiloxane and a conventional polymethylsiloxane were utilized as stationary phases. Many previously difficult to separate isomeric PAH (i.e., methylphenanthrenes/methylanthracenes, triphenylene/ chrysene, methylchrysenes, benzofluoranthenes, and pentaphene/benzo[b]chrysene) were identified. The relative abundances of the PAH in these samples were compared and correlated to the reaction conditions during their production. The relationship between abundance and structure for the identified PAH was also discussed.