Analysis of Total 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanol (NNAL) in Human Urine

A new method was developed for the analysis of metabolites of the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in human urine. The metabolites are 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronides (NNAL-O-Gluc and NNAL-N-Gluc). The sum of these metabolites, total NNAL, was measured with this method. Urine was treated with β-glucuronidase, which converts NNAL-O-Gluc and NNAL-N-Gluc to NNAL. After solvent partitioning and further purification on a liquid-liquid extraction cartridge and by high-performance liquid chromatography, total NNAL was quantified by gas chromatography with nitrosamine selective detection. The new method is accurate and precise, and the results are in good agreement with those obtained using the traditional method, which quantifies NNAL and its glucuronides separately. Levels of total NNAL ± SD (pmol/mg creatinine) were 2.60 ± 1.30 (n = 41) in smokers, 3.25 ± 1.77 (n = 55) in snuff-dippers, and 0.042 ± 0.020 (n = 18) in nonsmokers exposed to environmental tobacco smoke. The new method is faster and more sensitive than the traditional method and should greatly facilitate studies on human uptake of NNK.