Determination of four tobacco-specific nitrosamines in electronic cigarette liquids and aerosols by UPLC-QTOF-HRMS

To elucidate the concentrations of four tobacco-specific nitrosamines (TSNAs) in commercial e-cigarettes, analyze the correlation between TSNAs and Nicotine, and clarify the main sources of TSNAs in e-cigarettes. Ultra-high performance liquid chromatography with quadrupole time-of-flight high-resolution mass spectrometry (UPLC-QTOF-HRMS) was employed to determine the concentrations of four TSNAs in thirty-two commercially available e-cigarettes. The results demonstrated that the method exhibits excellent linearity and high mass accuracy. The limits of quantification (LOQ) of four TSNAs in e-cigarettes were 0.0010 - 0.0165 (e-liquids) and 0.0032 - 0.0554 (aerosols) ng·g-1. The limits of detection (LOD) of four TSNAs in e-cigarettes were 0.0011 - 0.0165 (e-liquids) and 0.0033 - 0.0537 (aerosols) ng·20 puffs-1. The recovery of four TSNAs ranged from 73.06% to 109.95%. The e-liquids contained: 0 - 33.970 (NNN), 0.063 - 15.654 (NNK), 0 - 10.033 (NAT), and 0 - 0.251 (NAB) ng·g-1. The aerosols contained: 0 - 60.662 (NNN), 0.021 - 9.435 (NNK), 0.202 - 29.866 (NAT), and 0 - 2.841 (NAB) ng·20 puffs-1. The correlation analysis results have shown that there was no significant correlation between the concentrations of four TSNAs and nicotine in e-cigarettes. The concentrations of four TSNAs in e-liquid containing tobacco extract were significantly higher than that in e-liquid without tobacco extract, suggested that the main source of TSNAs was tobacco extract. This method is fast, simple, highly sensitive, and has low detection limits. The approach taken can provide data support for the actual supervision of e-cigarettes, and evaluation of safety components, contributing to effective quality evaluation systems.