Multi-analyte approach for determining the extraction of tobacco constituents from pouched snus by consumers during use

BACKGROUND Snus is a smokeless oral tobacco product with a significant history of use in Sweden, where it is regulated under food legislation. Users place a small porous sachet or a pinch of loose snus between the upper jaw and cheek for approximately one hour, leading to partial intake of tobacco constituents. To understand user exposure to tobacco, a multi-analyte approach based on the extraction of pouches by methanol, ethanol and water was validated and applied to the measurement of various constituents, including nicotine, four tobacco-specific nitrosamines (TSNAs), propylene glycol, water, ammonium, nitrate, sodium, chloride, linalool, citronellol, linalyl acetate and geraniol, extracted from snus pouches during use by human consumers. RESULTS After validation against established single-analyte methods, the multi-analyte approach was used to determine constituent levels in snus pouches before and after one hour of use. Although the concentrations in the snus pouches varied from nanogram (e.g. TSNAs) to milligram (e.g. nicotine, sodium and propylene glycol) quantities (25.1 ng to 35.3 mg per 1 g pouch), the mean percentage extracted varied only from 19.2% for linalyl acetate to 37.8% for the TSNA 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) among all constituents analyzed. The TSNAs, some of which are known carcinogens, showed the highest percentage extraction (range 34.6%-37.8%). Measurement variability was low for all analytes, ranging from 2.4% (total TSNAs, NAT) to 9.5% (geraniol). By contrast, inter-subject variability ranged from 6.7% (NAB) to 52.2% (linalyl acetate), and was greater than 20% for eight of the constituents analyzed. Intra-subject variability ranged from 3.4% (citronellol) to 29.7% (geraniol). CONCLUSIONS Generally, less than a third of each constituent tested was extracted during one hour of snus use, independent of constituent concentration. The variable nature of in-use extraction was shown to be driven by inter-subject variability. The results provide insight into possible mechanisms controlling constituent extraction in the mouth during snus use, and provide reference data for the development of in-vitro laboratory systems for estimating extraction of tobacco constituents from snus.