Determination of 4-(methylnitrosamino)-4-(3-pyridyl)-butyric acid in tobacco, tobacco smoke and the urine of rats and smokers.

The potential endogenous nitrosation of nicotine and/or nicotine metabolites has led to speculation on the possible formation of 4-(methylnitrosamino)-4-(3-pyridyl)butyric acid (iso-NNAC) in smokers. A gas chromatographic method with thermal energy analytical detection is described for the determination of iso-NNAC in tobacco, tobacco smoke and urine. Sample pre-concentration is performed using C18 extraction cartridges prior to esterification of iso-NNAC using ethereal diazomethane solution. Sample clean-up includes chromatography on aluminum and silica, and fractionation using high-performance liquid chromatography. The detection limits for iso-NNAC in tobacco, tobacco smoke and urine are 2 ng/g tobacco, 0.1 ng/cigarette and 20 ng/l urine, respectively.