Anion Exchange and Nebulizer-Enhanced Online UV-Chemiluminescence Analyzer Coupled with LC-MS for Total and Novel N-Nitrosamines in Cigarettes and e-Juices

Quantification of total N-nitrosamines (TONO) is critical for assessing environmental carcinogens. UV-chemiluminescence (UV-CL) shows promise for TONO analysis; however, the data accuracy is limited by matrix interference and the analyte-specific method sensitivity. To overcome these challenges, we designed a new online UV-CL analyzer integrating anion exchange cartridges (AEC) and a homemade nebulizer. The AEC eliminates interference from a wide concentration range of NO₂^-. The nebulizer effectively introduces both volatile and less-volatile nitrosamines, achieving 98.4% photolysis while requiring only 14-53% of the UV dosage used in previous studies. Our analyzer achieved a universal calibration across structurally diverse N-nitrosamines, simplifying quantitative N-nitrosamine measurements. We further demonstrated its application by measuring TONO in authentic tobacco products. Compared to liquid chromatography mass spectrometry (LC-MS), the analyzer obtained consistent kinetic results when monitoring the reaction between NO₂^- and nornicotine, supporting its application in kinetic studies. Moreover, our preliminary analysis of flavored e-juices shows that they could contain up to 0.24 μmol/g of TONO, which could increase further when an environmental level of NO₂^- (6.7 mg/L) is present. Comparing results obtained using the analyzer and LC-MS, known tobacco-specific nitrosamines (TSNAs) account for less than 5.5% of TONO, indicating that most N-nitrosamines in tobacco are unknown. This led to the tentative identification of two new N-nitrosamines: pyridine-methylated N-nitrosoanatabine and pyridine-methylated N-nitrosoanabasine using high-resolution HPLC-MS/MS. Our results supported the feasibility of using the UV-CL analyzer for rapid TONO measurements and highlighted the need to monitor N-nitrosamine contamination in e-juice and tobacco products.