Levels of the nicotine analog 6-methyl nicotine as a naturally formed tobacco alkaloid in tobacco and tobacco products

S-6-methyl nicotine (S-6MN) has appeared as a nicotine substitute in commercial electronic e-cigarette products and pouches, including with the claim that such use is not regulated under current U.S. law. This work describes an analytical chemistry based search for the natural S/R presence of 6MN and three other MN compounds in additive-free cured leaf tobaccos and in multiple commercial tobacco products. The samples were extracted using 5 N NaOH, then methyl t-butyl ether. The extracts were analyzed using gas chromatography (GC) with mass spectrometric (MS) detection, and liquid chromatography (LC) with high resolution MS/MS detection. GC peaks with the correct retention times and MS patterns were found and confirmed for 6MN. Further confirmation for the presence of 6MN was obtained by LC/MS/MS. The all-sample average level of 6MN was determined to be 0.32 µg per g of tobacco material; the levels were too low to determine the S/R distributions. For 2MN, strong but not fully confirmed (*) evidence was obtained; analytical results are presented for 2MN* at an all-sample average level of 0.10 µg per g of tobacco material. No evidence for either 4MN nor 5MN was found. Because most commercial nicotine is as extracted and purified from tobacco, 6MN can be expected in all such nicotine, and therefore in most nicotine-containing e-cigarettes (ENDS) as well as reagent-grade nicotine. Analyses of GC/MS data from past analyses of nine high-nicotine e-cigarette liquids purchased during the period 2018 to 2022 indicated a mean ± 1 s.d. result for 6MN of 6.3 ± 1.4 µg/mL.