Chemical characterization of smokeless tobacco products from South Asia: Nicotine, unprotonated nicotine, tobacco-specific N′-Nitrosamines, and flavor compounds

•Certain South Asian smokeless tobacco, including ready-to-use products, are not well characterized.•In this study, we measured pH and concentrations of nicotine, tobacco-specific nitrosamines, and flavor compounds.•Products had a wide range of moisture (4.0–46.6%), pH (pH 4.99–10.0), total nicotine (0.39–35.2 mg/g) and unprotonated nicotine (<0.01–11.9 mg/g).•Two khaini products analyzed contained higher levels of N′-Nitrosonornicotine, a compound associated with oral cancer.•Understanding the constituents in these products is necessary for characterizing potential harm as these products become more available worldwide.