Enantiomeric composition of N '-nitrosonornicotine and N '-nitrosoanatabine in tobacco

The tobacco-specific nitrosamines N'-nitrosonornicotine (NNN) and N'-nitros oanatabine (NAT) are found in substantial quantities in unburned tobacco. A lthough this has been documented in many previous studies, no data are avai lable on the enantiomeric composition of these nitrosamines, which both hav e a chiral center at their 2'-positions. We used chiral stationary phase ga s chromatography with nitrosamine-selective detection to determine the enan tiomeric composition of NNN and NAT in moist snuff, chewing tobacco, and ci garette tobacco. (S)-NNN kcomprised 75.0 +/- 8.83% (SD) (n = 12) of total N NN while (S)-NAT comprised 82.6 +/- 1.44% (n = 12) of total NAT. Levels of the (S)-enantiomers of NNN and NAT were generally similar to those of the c orresponding secondary amines, nornicotine and anatabine, suggesting a prec ursor to product relationship. Nitrosation of (S)-nicotine at pH 7.0 produc ed >99% (S)-NNN. These results suggest that nornicotine is a significant pr ecursor of NNN in tobacco. The results of this study provide new insights i nto the structures and precursors of tobacco-specific nitrosamines in tobac co products.