Selective and simultaneous determination of trace amounts of 5H-benzo[b]carbazole and naphthacene in a variety of analogous chemical using the zone-melting technique and synchronous fluorescence spectrometry

Abstract

5H-Benzo[b]carbazole and naphthacene can be selectively separated from analogous species by zone melting in a bibenzyl system because of the formation of solid solutions with distribution coefficients almost equal to unity. In practice, a uniform mixture of a polycyclic aromatic sample (10–100 mg) with bibenzyl containing 0.1% of 2,6-di-tert-butyl-4-methylphenol (3.6 g) was zone melted in a 4 mm i.d. glass tube. Only the first 0.2–0.4 fraction of the zone-molten ingot was cut off and the amounts of the two analytes in this fraction were simultaneously measured by using synchronous fluorimetry. Each content of the analytes in the original sample can be calculated from the resulting amount and other experimental data. The method was applied directly to the determination of parts per million levels of 5H-benzo[b]carbazole and naphthacene in commercially available chrysene, pyrene, carbazole and some other chemicals.