Nitrate as an indicator of tobacco-specific alkaloid and nitrosamine content in smoking tobacco products

Tobacco-specific nitrosamines (TSNAs) are potent carcinogens formed from tobacco-specific alkaloids (TSAs) and nitrosating agents during processing. This study employed three validated isotope dilution LC-MS/MS methods to simultaneously quantify nitrate, nitrite, TSAs, and TSNAs in 29 smoking tobacco products, including less-studied types such as Zozial, Bidi, and Hookah. Zozial, grown without fertilizer, showed the lowest nitrate (705 µg/g) and TSNA (45.2 ng/g) levels, while commercial cigarettes and Bidis had the highest—up to 7379 µg/g nitrate and 1545 ng/g TSNAs. Nitrate was strongly correlated with both TSA and TSNA concentrations (r = 0.64–0.85, p < 0.001), whereas nitrite and pH were not. Multiple linear regression confirmed nitrate as the primary determinant of TSNA formation and alkaloid-to-TSNA conversion efficiency. These findings highlight nitrate’s central role in TSA and TSNA formation and suggest that nitrate quantification may serve as a practical marker for nitrosamine burden and a target for tobacco product regulation.