Application Of Tandem Chromatography Technology In Chiral Separation And Analysis Of Alkaloids And Menthol In Tobacc

Chirality is a fundamental property of nature,and chiral isomerism exists in most compounds,whether natural or synthetic.The chemical compounds are very important factors affecting tobacco quality,and in most cases only one stereo-isomeric form has a positive aroma and without physiological toxicity.The reported studies on tobacco aroma compounds mainly focused on their aroma and taste,with little in-depth research on chiral analysis and quality control.Tobacco extracts（mainly alkaloids）and menthol additives are widely used in tobacco products（especially novel tobacco products）,and their chiral distribution and origin have a significant impact on the sensory quality and safety of cigarette.It is of great significance to study the effects of different configurations of alkaloids and menthol enantiomers on the sensory of cigarette,and providing technical support for the quality control and improvement of traditional tobacco products and novel tobacco products.However,the chiral separation of alkaloids and menthol enantiomers in tobacco has become the core of restricting the identification technology problem.Based on the above,two efficient,green,sample-compatible methods for the separation and analysis of menthol and alkaloids enantiomers were established,and uses for the chiral separation and analysis of alkaloids and menthol enantiomers in different tobacco samples.A more In-depth and comprehensive studies on the configuration analysis of alkaloids and menthol enantiomers were conducted,which led to the establishment of identification methods for alkaloids and menthols,providing technical support for the identification of the origin and authenticity of the additives.The proposed method provides a novel strategy for the food industry to effectively separate multiple chiral substances in complex matrixes.The main research contents and results are as follows:（1）The separation and analysis methods for eight alkaloids and eight menthol enantiomers in tobacco samples were established for the first time.An analytical method based on a C₁₈ column-chiral column tandem technique combined with liquid chromatography spectrometry was proposed to separate the 4 pairs of alkaloids enantiomers（R-（+）-nicotine/S-（-）-nicotine,R-（+）-cotinine/S-（-）-cotinine,S-（-）-Anabasine/R-（+）-Anabasine and S-（-）-Anatabine/R-（+）-Anatabine）.A method based on two chiral capillary column tandem technique combined with gas chromatography-mass spectrometry was firstly proposed to separate the 4 pairs of menthol enantiomers.（（+/-）-menthol,（+/-）-neomenthol,（+/-）-isomenthol,（+/-）-neoisomenthol）).The above two established separation methods obtained ideal detection limits,correlation coefficient and spike recoveries,and can meet the requirements for the separation,analysis and detection of the enantiomeric isomers of alkaloids and menthol in complex tobacco matrices.（2）The enantiomeric content and ratio difference of 4 pairs of alkaloids enantiomers in tobacco and cigarette smoke of different brands were analyzed.The results show that the enantiomeric distribution of alkaloids in different tobacco samples differed in content and ratio,showing different distribution characteristics.The different distribution characteristics of the alkaloid enantiomers can provide an experimental basis for discovering the origin of the product,distinguishing different brands or varieties of tobacco samples and discriminating between real and fake cigarettes.In addition,a study on the identification of Cherry-Red tobacco was also conducted using the conformational distribution of alkaloid enantiomers.The results showed that the difference in the conformational distribution characteristics of the alkaloid enantiomers,especially the proportion of R-nicotine in the nicotine is five times higher than that of R-nicotine in ordinary tobacco,can be used to distinguish Cherry-Red tobacco from ordinary tobacco.This can provide the tobacco industry with accurate and objective indicators for distinguishing Cherry-Red tobacco from ordinary tobacco,and then provide scientific data and technical means for the selection and identification of tobacco materials.（3）The enantiomeric content and ratio difference of 4 pairs of menthol enantiomers in the different menthol-type cigarette and natural Mentha plant samples were analyzed.The results showed that not only（-）-menthol,which has a positive flavor,but also other menthol isomers with a negative flavor were detected in some menthol-cigarette samples.This finding is conductive manufacturers to adopt stricter quality control measures when adding menthol to products to ensure the positive organoleptic characteristics of the final products.In addition,the different percentages of menthol isomers in different samples show different distribution characteristics,which can provide a theoretical basis for verifying the origin of the product,differentiating between different tobacco samples,and distinguishing between real and fake cigarettes.To further verify the origin of menthol in menthol-tobacco products,the enantiomeric content and distribution of menthol in 23 natural menthol plants were analyzed,and the results showed that the presence of（+）-menthol in the samples could be used as an identifying factor to discriminate between synthetic and natural sources of menthol.Finally,the menthol enantiomers conformation analysis technique was used to conduct a study on the identification of real and fake cigarettes.The results showed that the identification and difference analysis of menthol enantiomers in real and fake cigarette cartridges allowed for the accurate identification of fake cigarettes.