Simultaneous determination of four tobacco-specific N-nitrosamines in mainstream smoke for Chinese Virginia cigarettes by liquid chromatography-tandem mass spectrometry and validation under ISO and "Canadian intense" machine smoking regimes

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determining four tobacco-specific N-nitrosamines (TSNAs) in mainstream smoke from Chinese Virginia cigarettes was developed. Mainstream cigarette smoke particulate matter was collected on a Cambridge filter pad, further extracted using 100 mM ammonium acetate after 100 microL internal standard addition, and subsequently analyzed with LC-MS/MS. The limit of detection for NNN, NNK, NAT and NAB were 0.006, 0.013, 0.003 and 0.021 ng mL(-1) respectively, with a linear calibration range spanning 1-200 ng mL(-1). Intra- and inter-day precision for four TSNAs ranged from 3.3% to 8.5% and 2.3% to 10.1%; recovery was between 89.1% and 104.9% for Chinese Virginia cigarettes. The proposed method was applied to evaluate TSNAs yields for 39 commercially available cigarettes in Chinese market under ISO and "Canadian intense" machine smoking regimes, on the ground that it comes closest to representing smoke deliveries from human smoking. Total TSNAs emissions are more than double under the Canadian regime. TSNAs:nicotine ratios were used in our assay to show any differences in yield from different brands. TSNAs:nicotine levels show more than a 10-fold difference across brands and types (Chinese Virginia cigarettes and blended cigarettes) in the Chinese market.