| With the rapid development of analytical science,the complexity of analytical sample,higher requirements have been put forward to develop analytical technology,sample analysis technology tends to be fast,efficient,miniature and automatic.In analytical science,not only sophisticated detection equipment,but also excellent sample pretreatment techniques are needed.According to the different pretreatment techniques,the common sample pretreatment techniques such as phase distribution and phase adsorption are reviewed in this paper,and their principles,characteristics and application are discussed respectively.The aroma components in tobacco leaves have a decisive effect on the aroma quality of cigarettes,but its content is low and variety.At present,the determination of tobacco is mainly carried out by simultaneous distillation extraction,supercritical fluid extraction and solid-phase microextraction,and analysed by GC-MS.In this paper,C18 column solid phase extraction and liquid-liquid extraction were used for pretreatment,and high performance liquid chromatography combined with ion trap mass spectrometry was used to determine the aroma components in tobacco.At the same time,the principle and characteristics of common sample analysis methods and liquid chromatography combined with mass spectrometry are also briefly described in this paper.After full investigation of literature,the mainly research works in this paper as follows:1.Optimated the conditions of HPLC-MS,mobile phase A was 0.1%ammonium acetate solution,mobile phase B was methanol,the flow rate was 0.3 ml/min,the gradient elution conditions were determined as follows:0 min,100%A;8 min,70%A;16 min,40%A;24 min,20%A;30 min,0%A;35 min,100%A;40 min,100%A.At the same time,the scanning mode,parent ion,product ion,declustering potential and collision energy of each flavor component were determined.2.Tobacco extract contained a lot of saccharides,which had a matrix effect on the detection and affected the measurement results.In this paper,C18 column solid phase extraction and liquid-liquid extraction were used to the purification and enrichment,then compared the results.C18 extraction method refers to the extraction of smoke samples by methanol,filtered by the filter.Then,the C18 column was used as the solid phase extraction column and 60%methanol-water solution as the eluent,sample extraction buffer was concentrated by solid phase extraction.Finally,the extract was injected to HPLC-MS for analysis.The conditions of mass spectrometry,eluent dosage,loading amount,purification elution conditions and sugar matrix elution conditions were optimized.After the sample was extracted with a certain proportion of methanol-water solution,the solution was reextracted with dichloromethane,then the extract was concentracted by nitrogen purging system,finally the concentrates were injected into HPLC-MS for analysis.3.A novel shunt was designed for the analysis.A method for the analysis of important aroma components in tobacco by Post-Column Matrix Time Shunt-HPLC-MS was established.The tobacco samples were extracted by methanol solution and directly analyzed by HPLC-MS.According to the different retention time of flavor components and saccharide,the chromatographic effluent was switched and shunte to eliminate the interference of the saccharide to ionization of the fragrance components.The important aroma components in tobacco were analyzed by this method.4.After digestion of the tobacco samples,the enrichment solution treated in the neutral buffer solution is directly injected into the HG-AFS for analysis.The sensitivity is high,which can reach the lower detection limit and can eliminate the the interference of heavy metal ions to the determination of selenium in tobacco and can achieve the effective determination of trace selenium in tobacco extraction. |
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