Use of autoclave extraction-supercritical fluid chromatography/tandem mass spectrometry to analyze 4-(methylintrosamino)-1-(3-pyridyl)-1-butanone and N’-nitrosonornicotine in tobacco

• Published in: Journal of Chromatography A 2019-06, Vol.1595, p.207-214
• Main Authors: Deng, Huimin, Tang, Gangling, Fan, Ziyan, Liu, Shanshan, Li, Zhonghao, Wang, Ying, Bian, Zhaoyang, Shen, Wei, Tang, Sheng, Yang, Fei
• Format: Article
• Language: English
• Subjects: 4-(methylintrosamino)-1-(3-pyridyl)-1-butanone; Autoclave extraction; N’-nitrosonornicotine; SFC-MS/MS; Tobacco specific nitrosamines
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2019.02.053

•A SFC-MS/MS method was developed and validated for NNK and NNN analysis.•Peak splitting resulted from E/Z isomerism was fully eliminated.•Autoclave extraction was employed to extract matrix bound NNK.•The method was successfully applied to analyze NNK and NNN in tobaccos.•Fractions of matrix bound NNK in 3 typical tobacco types were determined. 4-(methylintrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N’-nitrosonornicotine (NNN) are the most prevalent and toxic tobacco specific nitrosamines (TSNAs). Due to their carcinogenicity, knowledge of the composition of NNK and NNN in tobacco is necessary. Herein, a sensitive and rapid method, which employs autoclave extraction-supercritical fluid chromatography/tandem mass spectrometry (SFC-MS/MS), has been developed for the analysis of NNK and NNN in tobacco. Both water-soluble and matrix-bound NNK and NNN were extracted with 100 mM ammonium acetate in an autoclave (130 °C, 4 h), and the aqueous extract was subjected to solvent replacement prior to SFC-MS/MS analysis. NNK and NNN were effectively separated within 5 min by using supercritical CO2 as the main mobile phase coupled with a co-solvent of methanol. Excellent linearity was obtained with coefficients of determination (R2) greater than 0.9997 in the range of 1–160 ng/mL and 5–800 ng/mL for NNK and NNN, respectively. The recoveries were in the range of 92.5–110.0% at different spiked levels of real samples. 12 tobacco samples which include 3 typical tobacco varieties of burley, flue-cured, and oriental tobaccos had been analyzed, and the fraction of matrix-bound NNK was determined as well. In addition, a comparison between the proposed SFC-MS/MS method and a validated liquid chromatography tandem mass spectrometry (LC–MS/MS) internal standard method was conducted. Both techniques exhibit comparable analysis results, but peak splitting of NNN was observed by LC-MSMS due to the existence of E/Z isomers, while SFC-MS/MS offers great improvement through elution condition optimization, demonstrating the applicability of SFC-MS/MS as an alternative tool for NNK and NNN analysis.