Chemical Studies on Tobacco Smoke: VI. The Determination of Carbazoles in Cigarette Smoke

A method was developed for the enrichment of carbazoles from cigarette smoke. It involves a distribution between two solvent systems, column chromatography, and, finally, separation of a carbazole concentrate into individual components by gas chromatography. The major components in the chromatogram were collected after the final separation and were then identified by mass spectra. Since the latter method showed similar fragmentation patterns for five carbazoles and 2- and 3-phenylindoles, mass spectra appeared especially suitable for their identification. Carbazole, 1-methylcarbazole, 4-methylcarbazole, 3-phenylindole, a mixture of 2- and 3-methylcarbazole and, tentatively, a dimethyl- or ethylcarbazole and 2-phenylindole were identified in cigarette smoke. The relevancy of mass spectra for the identification of carbazoles and 2- and 3-phenylindoles is discussed. For the quantitative analysis of carbazoles and 3-phenylindole, carbazole-10-C¹⁴ was employed as internal standard. The radioactive compound was synthesized on a microscale from phenylhydrazine-1-C14 by the Borsche method with a 58% yield. The smoke of 100 U.S. nonfilter cigarettes of 85 mm length contains 100 µg of carbazole, 23 µg of 1-methylcarbazole, 19 µg of 2- and 3-methylcarbazole, 9.8 µg of 4-methylcarbazole and 31 µg of 3-phenylindole. The concentrations of the tentatively identified dimethyl-, or ethylcarbazole and 2-phenylindole were below 1.0 µg.