Use of a gas-tight syringe sampling method for the determination of tobacco-specific nitrosamines in E-cigarette aerosols by liquid chromatography-tandem mass spectrometry

We report here a sampling method using a gas-tight syringe (GTS) in the determination of tobacco-specific nitrosamines (TSNAs) in aerosols from electronic cigarettes. The method is based on extraction with a solvent at the same time as the aerosol is introduced into a GTS. The analytes were dissolved in the solvent after it had been injected into the GTS and the extract was then directly injected into a liquid chromatography-tandem mass spectrometry system. The optimum extraction conditions for the TSNAs were: solvent, methylene chloride; volume, 10 mL; and shaking time, 3 min. The proposed GTS method was compared with conventional impinger methods. The GTS method showed good recoveries of 98-103% with a small relative standard deviation of 2%. The amounts of TSNAs per 50 mL puff were 3.5-45.5 pg for N'-nitrosonornicotine, 3.5-759.5 pg for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, 3.5-164.5 pg for N'-nitrosoanabasine, and 3.5-612.5 pg for N' -nitrosoanatabine in the aerosols from 50 brands of electronic cigarettes from 11 different companies purchased in Korean shops. When the developed method was applied to aerosols from electronic cigarettes using prepared replacement liquids containing TSNA precursors, no TSNA was observed. Therefore we suggest that the TSNAs were not formed during the operation of the electronic cigarettes. We used the same method to determine the concentrations of TSNAs in 10 conventional cigarettes produced by five different companies and purchased from shops in Korea. The total observed concentrations of TSNAs in the electronic cigarettes were about 100-fold lower than in the conventional cigarettes.