Study On Application Of New Technology Of Mass Spectrometry And Hyphenation To Tobacco Chemistry

Smoking and health is an important scientific problem which is concerned with the development of society. In recent years, many scientists of tobacco chemistry have been committed to minimizing the toxicity of harmful ingredients on human body and the amount of cigarette tar which contained primary harmful ingredients. However, as the cigarette tar decreased, a lot of flavor components would be lost which caused the cigarette smell falling at the same time. In order to effectively implement and evaluate the goal of harm reduction, on the one hand flavor additives need to be studied to compensate the loss of flavor while the cigarette tar is reduced; on the other hand some new analytical methods for fast, selective and sensitive determination of some strongly carcinogenic ingredients in cigarette smoke need to be established.In this study, some new technology in mass spectrometry (MS) and hyphenation was applied in the study of tobacco chemistry. Thermal decomposition mechanism of glycoside flavor precursor was studied by using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and photoionization mass spectrometry. Different pyrolysis modes were observed. Some new analytical methods for rapid, selective, and sensitive determination of four tobacco-specific nitrosamines (TSNAs) were developed. There are five parts in this dissertation and each section is as follows:Section 1: The basic concepts on MS and hyphenation technology are briefly described. The applications of these techniques in tobacco chemistry are reviewed. Then, the study of glycoside flavor precursor and strong carcinogenic TSNAs in tobacco and its smoke are introduced. In the end, the research idea and main way of study is designed.Section 2: Study on pyrolysis mechanism of two glycosides by pyrolysis-gas chromatography-mass spectrometry.Glucosides of benzyl alcohol and 4-methoxybenzyl alcohol were synthesized. The pyrolysis behavior and pyrolysis products of two glycosides were studied by Py-GC/MS at the temperature of 300, 500, and 700°C. Py-GC/MS was used for the qualitative and semi-quantitative analysis of the pyrolysis products. Different pyrolysis modes for glucoside of benzyl alcohol and glucoside of 4-methoxybeznyl alcohol were observed by identifying the pyrolysis products and comparing the peak areas of products at the temperature of 300°C.Section 3: Thermal decomposition study of two glycosides by synchrotron photionization mass spectrometry. The thermal decomposition behaviors of two glycosides, glucoside of benzyl alcohol and gluscoside of 4-methoxybenzyl alcohol were studied by using tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Several pyrolysis products and intermediates were identified by the measurement of photoionization mass spectra at different temperature of 300, 500, and 700°C with the variation of photon energy. It was found that two glycoside showed different pyrolysis modes at the temperature of 300°C. For glucoside of benzyl alcohol the main pyrolytic way was the cleavage of O-glycosidic bond producing much benzyloxy group which was the precursor of benzyl alcohol. For glucoside of 4-methoxy alcohol, the main rupture of 4-methyloxybenzyl-oxygenic bond was observed, forming a large amount of 4-methyloxybenzyl.Section 4: Study on an UPLC-MS3 method for the analysis of four TSNAs in mainstream cigarette smoke.A new ultra-high-pressure liquid chromatography/MS3 (UPLC-MS3) method has been developed and validated for the quantitative determination of four major TSNAs in mainstream cigarette smoke using MS3 scan mode on a hybrid triple quadrupole-linear ion trap mass spectrometer. The new method combining the UPLC with MS3 scan mode offers decreased sample analysis time, good selectivity and sensitivity. By the use of UPLC column, the complete chromatographic baseline separation of four TSNAs was obtained. The quantitative ion of each TSNA was selected by the second fragmentation from each second precursor ion. This method could be used as an effective approach to significantly improve the detection capability for TSNAs in complex matrices.Section 5: Study on analysis of four TSNAs by UPLC-QqLITA new method for sensitive and rapid determination of four TSNAs was developed by using an ultra-high-pressure liquid chromatography tandem mass spectrometry. This new method could be used to simultaneous quantitative and qualitative analysis of four TSNAs in cigarette smoke, due to the use of linear ion trap (LIT) mass analyzer that was capable of maintaining higher sensitivity in full scan mode than quadrupole (Q) mass analyzer. The problem of interference by matrix effect could be avoided by the extraction of different ions during quantitative process. This method was suitable for the analysis of super-low TSNAs in mainstream cigarette smoke.