Combined Analysis of the Tobacco Metabolites Cotinine and 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol in Human Urine

[Image: see text] Two of the most widely measured compounds in the urine of people who use tobacco products are cotinine, a major metabolite of the addictive constituent nicotine, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a metabolite of the powerful lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Thousands of analyses have been reported in the literature, carried out exclusively, to the best of our knowledge, by separate methods. In the study reported here, we have developed a sensitive, accurate, and precise liquid chromatography-electrospray ionization-tandem mass spectrometry-selected reaction monitoring method for the combined analysis of total cotinine (the sum of cotinine and its glucuronide) and total NNAL (the sum of NNAL and its glucuronide). The new method quantifies naturally occurring [(13)C]cotinine to minimize problems associated with the vast differences in concentration of total cotinine and total NNAL in urine. This method should greatly facilitate future determinations of these important compounds.