Analysis of total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in smokers' blood

The sum of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides (total NNAL) is an excellent biomarker for uptake of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. Although numerous studies have examined levels of total NNAL in the urine of people who use tobacco products, few have quantified this biomarker in blood, and the available methods used relatively large amounts of blood. A method is urgently needed for the analysis of total NNAL in blood, the fluid most commonly stored in molecular epidemiologic studies. We developed a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method for the analysis of total NNAL in 1-mL samples of plasma. LC-ESI-MSMS provides both high-sensitivity and structural information supporting analyte identity. The method is practical and sensitive, with a detection limit of 8 fmol total NNAL/mL plasma. Levels of total NNAL averaged 42 ± 22 (SD) and ranged 1.7 to 88 fmol/mL plasma in 16 smokers; NNAL was not detected in the plasma of five nonsmokers. These results show that total NNAL can readily be quantified in 1-mL plasma samples.