Quantitation of Tobacco Lipids

The hexane extractable fraction of tobacco is important because its lipid components affect leaf quality and are precursors of polynuclear aromatic hydrocarbons (PAH) in smoke (1,2). Swain et al. (3) reported a qualitative analysis of this fraction in 1961. However, 69% of the fraction was reported as resinous material and was not identified. Cook et al. (4) in 1968 fractionated a hexane extract according to polarity and molecular weight by utilizing counter-current distribution and gel permeation chromatography. These techniques permitted nondestructive, quantitative recovery of components for identification by various analytical methods. The molecular weights of 70% of the nonbasic compounds in the hexane extract were found to be below 800 daltons, suggesting the presence of relatively simple components. Most quantitative studies of the major tobacco lipids have been limited to individual compounds or classes of compounds. Thus, fatty acids and their esters (5–8), sterols and steryl esters (9–13), neophytadiene (14,15) hydrocarbon waxes (15,16) and solanesol (17,18), which constitute the major tobacco lipids, have been quantitated by various research groups. In most instances only one or two of these compounds or classes of compounds have been analyzed in the same tobacco sample.