Simultaneous Extraction and Derivatization of Volatile Organic Acids in Flue-Cured Tobacco with Headspace Solid-Phase Microextraction Followed by GC-MS

Simultaneous quantification of nicotine salts in e-liquids by LC-MS/MS and GC-MS

Nicotine salts, formed by nicotine and organic acids, are commonly added to electronic cigarette liquids for their ability to provide desirable sensory effects. Analytical strategies have been developed to detect the types of organic acids and nicotine levels, but methods for directly measuring nicotine salts are still desirable. Herein, a novel approach is presented for the simultaneous quantification of non-volatile and volatile nicotine salts via liquid chromatography/tandem mass spectroscopy (LC-MS/MS) and gas chromatography/mass spectroscopy (GC-MS). This approach was validated with recovery experiments, which yielded recovery values between 92.0% and 110.8%. This method is the first technique for quantifying multiple nicotine salts that could be present in commercial e-liquids. Without using derivatization steps, different nicotine salts could be detected rapidly and conveniently. This new method was demonstrated with 10 e-cigarette liquid samples, providing satisfactory outcomes. It could be used to study organic acids and protonated nicotine in e-liquids and the release behaviour of nicotine salts in electronic cigarettes.

Study of metabolite differences of flue-cured tobacco from different regions using a pseudotargeted gas chromatography with mass spectrometry selected-ion monitoring method

A pseudotargeted method based on gas chromatography and mass spectrometry with selected-ion monitoring was established to investigate the metabolite differences of flue-cured tobacco from three different growing regions. The mixed solvent of acetonitrile/isopropanol/water (3:3:2, v/v/v) was chosen as the optimal extraction system based on the good repeatability and extraction efficiency. A self-developed software coupled with commercial software was used to establish the pseudotargeted method including 289 peaks and 47 groups. Multivariable statistical analysis indicated that tobacco samples can be obviously separated based on the geographical origins. On the basis of a Mann-Whitney U test, organic acids, phenols, and alkaloids had higher levels in Hunan province. In contrast, a large proportion of amino acids (including L-tyrosine, L-proline, and serine), sucrose, and linoleic acid were the highest in Yunnan province. Meanwhile, multiple metabolic pathways (including carbohydrate metabolism, tricarboxylic acid cycle, and nitrogen metabolism) were influenced by growing regions. Twenty-eight differential metabolites, which had great contributions to the classification of tobacco samples of three growing regions, were further defined. The results demonstrated that the developed pseudotargeted method was a powerful tool to investigate the metabolic profiling of tobacco leaves and discriminate tobacco leaves of different growing regions.