An LC-MS/MS Method for the Quantification of Tobacco-Specific Carcinogen Protein Adducts

4-(Methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its major metabolite 4-(methylnitrosamino)-l-(3-pyridine)-l-butanol (NNAL) are tobacco-specific lung carcinogens. Methods have been developed to quantify NNK- and NNAL-specific DNA adducts in preclinical samples but are not feasible to translation due to limited access to target tissues for sufficient DNA. In addition, NNAL-specific DNA or protein adducts have never been detected in clinical samples, which are critical to assess the physiological relevance of NNAL bioactivation and carcinogenesis. We herein reported a highly sensitive and specific LC-MS/MS method to quantify the hydrolyzed product, 1-(3-pyridyl)-1,4-butanediol (PBD), from NNAL-induced protein adduct. This method was applied to a variety of biological samples to assess tobacco exposure and NNAL bioactivation.