Paraffins of tobacco Ieaf were separated by column chromatography on silicic acid. Leaf paraffins were fractionated from other wax constituents by chromatography in a definite sample to substrate to solvent ratio. The developed method was used to evaluate the transfer of paraffins and neophytadiene from leaf to smoke in a reference cigarette. Gas chromatographic separations were performed on a high-temperature liquid phase. Gas chromatography in conjunction with mass spectrometry was used to determine the paraffin composition of a representative flue-cured tobacco, a reference cigarette tobacco, and smoke condensate. It was concluded that paraffins were probably transferred to smoke relatively unchanged, while neophytadiene underwent some pyrolytic decomposition.
M. E. Snook, R. F. Severson, R. F. Arrendale, H. C. Higman and O. T. Chortyk
The methyl, multi-methyl, and ethyl derivatives of the polynuclear aromatic hydrocarbons (PAH) of cigarette smoke condensate (CSC) were isolated from the neutrals by silicic acid chromatography, solvent partitioning and gel chromatography. The procedure yielded a relatively pure PAH isolate amenable to further identifications. The multi-alkylated PAH were concentrated in the early gel fractions with parent and higher ring PAH found in subsequent gel fractions. It was shown that CSC is very rich in alkylated PAH, and their successful identification required extensive use of gas and liquid chromatography and ultra-violet and GC - mass spectrometric techniques. High-pressure liquid chromatography (HPLC) separated individual isomers of the alkylated PAH in complex GC peaks. PAH from indene to pentamethylchrysene were found. This report concludes our identification studies on the PAH of CSC and complements our two previous reports in this journal. Collectively, our studies have identified approximately 1000 PAH of cigarette smoke condensate and have led to the development of methods for the routine quantitation of PAH in smalI quantities of cigarette smoke condensate.
R. F. Severson, W. S. Schlotzhauer, R. F. Arrendale, M. E. Snook and H. C. Higman
Tobacco, its petroleum ether (PE) extract, and the residual extracted tobacco (marc) were pyrolyzed at 650-750°C, 650-850°C, and 700°C, respectively. Analyses of the polynuclear aromatic hydrocarbons (PAH) produced showed that the pyrolysis of the tobacco and the PE extract at 700°C produced PAH profiles comparable to those found in cigarette smoke condensate (CSC). The data indicated that most of the alkyl PAH and the major PAH in cigarette smoke are derived from the PE extractables of tobacco. The constituents of the marc were the major precursors for phenols, oxygenated PAH, and Iow molecular weight acids; and those of PE extract were the major producers of high molecular weight acids.
M. E. Snook, R. F. Severson, H. C. Higman, R. F. Arrendale and O.T. Chortyk
A neutral fraction of cigarette smoke condensate, which had shown biological activity and was known to contain polynuclear aromatic hydrocarbons (PAH), was fractionated by analytical gel filtration chromatography. These gel fractions were subjected to gas chromatographic separation and their components were identified by relative GC retention times, UV spectra, and mass spectral data. More than 300 PAH, ranging from indene to the dimethylbenzopyrenes, were characterized. This method of isolation has yielded fractions which were more amenable to definitive identifications. The criteria used for identification are tabulated for all the identified PAH compounds.
H. C. Higman, R. F. Severson, O. T. Chortyk and R. F. Arrendale
A pyrolytic method for evaluating the smoke properties of tobacco materials for their potential to produce biologically significant smoke phenols and PAH has been applied to close-grown tobacco, in comparison to conventionally grown tobacco. Analyses were performed on the lipids of tobacco samples to attempt correlations with amounts of polynuclear aromatic hydrocarbons in pyrolyzates. Relative to a standard flue-cured tobacco, the close-grown tobacco samples contained lower nicotine, neophytadiene and hydrocarbon levels, and lower sterols, solanesol and fatty acid levels. Close-grown tobacco pyrolyzates contained equivalent PAH levels and higher levels of phenols. Based on the pyrolysis data, the close-grown tobaccos do not offer a more desirable smoking product than conventionally grown flue-cured tobaccos. However, the lower levels of nicotine and higher amounts of smoke phenols may possibly make the close-grown materials suitable for inclusion into low-nicotine tobacco sheet products.
A gel filtration chromatography method was developed for the isolation and concentration of the high molecular weight polynuclear aromatic hydrocarbons (PAH) contained in the most biologically active fraction of cigarette smoke condensate (CSC). The unusually complex mixture of large PAH found in CSC necessitated the use of preparative gas chromatography followed by high-pressure liquid chromatography to achieve separation and identification. Mass spectral, ultra-violet absorption, and chromatographic retention data were needed for the comprehensive identification of the large molecular weight PAH components of CSC. The majority of the more than 200 isolated compounds were identified. Compounds newly identified in CSC included 3,4-dimethylenepyrene, 3,4-trimethylenepyrene, cyclopenta(c,-d)pyrene, 4,5-methylenetriphenylene, benzo[b]perylene, and several dibenzofluoranthenes.