Nicotine that is found in natural tobacco is primarily (99%) the S-enantiomer. Conversely, the most common chemistry synthetic methods for generating nicotine yields a product that is approximately equal proportions of the S- and R-enantiomers. This suggests that tobacco-derived and synthetic nicotine can be determined by measuring the ratio of the two different enantiomers, although means exist for adjusting the relative levels of the enantiomers or performing a synthesis that only leads to the S-enantiomer. There is limited data on the relative physiological effects of these two enantiomers, especially in people. However, the studies to date indicate that (S)-nicotine is more potent than (R)-nicotine and (S)-nicotine causes stronger sensations or irritation than (R)-nicotine. Studies have not been adequate to determine the relative addictiveness of the two enantiomers in people. thumb|class=skin-invert-image|Structure of protonated nicotine (left) and structure of the counterion benzoate (right). This combination is used in some vaping products to increase nicotine delivery to the lung. Pod mod electronic cigarettes use nicotine in the form of a protonated nicotine, rather than free-base nicotine found in earlier generations.
Nicotine that is found in natural tobacco is primarily (99%) the S-enantiomer. Co.nversely, the most common chemistry synthetic methods for generating nicotine yields a product that is approximately equal proportions of the S- and R-enantiomers This suggests that tobacco-derived and synthetic nicotine can be determined by measuring the ratio of the two different enantiomers although means exist for adjusting the relative levels of the enantiomers or performing a synthesis that only leads to the S-enantiomer. There is limited data on the relative physiological effects of these two enantiomers, especially in peop,le. However, the studies to date indicate that (S)-nicotine is more potent than (R)-nicotine and (S)-nicotine causes stronger sensations or irritation than (R)-nicotine. Studies have not been adequate to determine the relative addictiveness of the two enantiomers in people thumb|class=skin-invert-image|Structure of protonated nicotine (left) and structure o.f the counterion benzoate (right). This combination is used in some vaping products to increase nicotine delivery to the lung. Pod mod electronic cigarettes use nicotine in the form of a protonated nicotine, rather than free-base nicotine found in earlier generations.