Simultaneous determination of five tobacco-specific nitrosamines in mainstream cigarette smoke by isotope dilution liquid chromatography/electrospray ionization tandem mass spectrometry.

Tobacco-specific nitrosamines (TSNAs) have been previously implicated as a source of carcinogenicity in tobacco and cigarette smoke. Accurate quantification of these chemicals is needed to help assess public health risk. We have developed and validated a specific and sensitive method to simultaneously measure five TSNAs in the particulate phase of mainstream tobacco smoke. Cigarette smoke particulate, produced using standardized machine smoking protocols, was collected on a Cambridge filter pad. The particulate matter was extracted using methylene chloride, back extracted into aqueous solution, further purified by solid-phase extraction, and analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry using isotopically labeled analogues as internal standards. Limits of detection for this method ranged from 0.05 to 1.23 ng/mL using an injection volume of 20 microL. A linear calibration range spanning 2.5-2500 ng/mL was adequate to measure TSNA levels in cigarette smoke. The method achieved excellent reproducibility and accuracy. The identity of each TSNA was established by chromatographic retention time, analyte-specific fragmentation patterns, and relative peak area ratios of two product/precursor ion pairs. This new method provides higher sensitivity, specificity, and throughput than earlier methods for TSNA determination.