【作者】 刘百战；

【导师】 苏庆德；

【作者基本信息】 中国科学技术大学 ， 分析化学， 2009， 博士

【摘要】 烟草和卷烟烟气是高度复杂体系,烟草中已经鉴定的化学成分达3800多种,烟气中鉴定的成分达4800多种。尽管毛细管气相色谱分离能力很高,但对烟草和烟气样品来说仍是不够的。多维气相色谱(MDGC)充分利用一维柱和二维柱固定相极性的差异,在非极性柱上难以分离的组分,到极性柱上一般可以获得较好的分离。另外,多维色谱的峰容量(GC×GC)也比一维色谱大大增加。由于固定相选择性和峰容量的双重改善,MDGC的分离能力远远大于常规毛细管气相色谱。八十年代后期,国外烟草行业利用MDGC,对烟草和烟气进行分析研究,展示了MDGC强大的分离能力。国内烟草行业在MDGC方面的研究和应用很少。MDGC在手性分析方面具有显著优势,国内外烟草行业尚无相关的研究报道。本论文对MDGC和全二维气相色谱(cMDGC)概念、原理、仪器和技术进展进行了深入和全面综述,对相关技术的特点进行了分析比较。对手性气相色谱固定相和手性分离策略也进行了较深入的探讨。在完全掌握MDGC技术的基础上,在仪器开发和方法学方面有一定创新。利用手性MDGC/MS系统,对烟草和烟气生物碱手性组成进行了分析研究,在烟草化学基础理论方面,有新的发现和建树。主要研究内容和结果如下:1.开发了全自动全电子压力控制的毛细柱-毛细柱MDGC系统。在SGEMDS-6890的基础上,用Y-型玻璃压合连接器替代中心切割阀,用GC的辅助电子压力控制模块(EPC)提供三路气体,一路提供中点压力,一路提供切割压力,一路气体驱动冷阱。新系统具有以下优势:惰性更好,死体积更小,稳定性更好,成本更低。以烤烟精油全分析为例,展示了本系统的强大分离能力。2.开发了全自动具备在线富集功能的大孔柱-毛细柱MDGC系统。在SGEMDS-2000的基础上,用GC控制的阀箱取代外部的独立控制单元,用GC柱箱内的限流毛细管取代外部的中点分流针型阀,用气动On/Off阀取代中点分流电磁阀,且驱动气体与中心切割阀共享。新系统的优点包括,一体化和自动化水平大大提高,气路设计更趋合理,限流管选择更简便,改造成本低廉。3.在MDGC方法学上有所创新。以毛细柱载气压力/流量软件为基础,提出了双柱载气恒流条件的设定方法,提出了限流管规格的估算方法,大大简化了多维气相色谱方法的开发手续。4.优化了烟草和烟气中尼古丁手性分离条件,首次用实验证实了烟气R-尼古丁的形成机理。尼古丁对映体获得基线分离,R-(+)-尼古丁相对比例的检测限低于0.5%。采用在线裂解-chiral-MDGC/NPD,发现S-尼古丁试剂的消旋化与热裂解进程具有高度的同步性。采用在线裂解-chiral-MDGC/NPD和裂解-GC/MS,发现烟草中S-尼古丁的消旋化与热裂解进程也具有高度的同步性。吸烟过程中,高温下S-尼古丁的消旋化是烟气R-尼古丁的来源。5.建立了烟草中14种生物碱的定量分析方法。利用MDGC/MS和MDGC/NPD,对不同种类的烟叶原料和不同类型卷烟烟丝进行了分析比较。6.建立了烟草中新烟草碱、降烟碱和假木贼碱的手性分析方法。利用简单溶剂萃取、三氟乙酰衍生化和chiral-MDGC/MS-SIM,样品前处理简便,重现性出色,RSD%小于1.5%。在不同类型的烟叶中,三种生物碱的旋光组成有规律性差异。根据三种生物碱的手性组成数据,主成分分析可将不同类型烟叶清楚地区分开来。更多还原

【Abstract】 Tobacco and cigarette smoke are among the most complex mixtures.More than 3800 and 4800 substances have been identified in tobacco and tobacco smoke, respectively.Although capillary gas chromatography has great separating capability,it is still very reluctant to analytical tasks of tobacco and tobacco smoke. Multi-dimensional gas chromatography（MDGC） can fully make use of selectivity differences of pre- and analytical columns.Those overlapped constituents on a non-polar pre-column normally get a satisfactory resolution on a polar analytical column.In addition to this,the peak capacity of MDGC（GC×GC） is also substantially increased than conventional one dimensional GC.Base on the double contributions of selectivity and peak capacity,the separating power of MDGC is drastically enhanced than the one dimensional GC.Since later in 1980s,the great separation capability of MDGC has been shown in the analysis of tobacco and tobacco smoke by foreign tobacco industries.However,the research and applications of MDGC techniques are rarely seen in domestic tobacco industry.MDGC has been widely used in enantiomeric analysis and has many advantages than single chiral GC column.However,there have been no related publications in tobacco industry.In this paper,concepts,theories,instrumentation and technique progress of MDGC and comprehensive two dimensional GC（cMDGC） have been extensively reviewed, features of the related techniques has been compared.The chiral GC stationary and tactics for chiral GC separation have also been reviewed.With a comprehensive understanding of MDGC techniques,innovative results have been obtained on aspects of instrumentations and analytical methodologies.Chirality of alkaloids in tobacco and tobacco smoke have been studied by MDGC/MS,some new findings involved in tobacco chemistry have been established.The major studies and results were shown as follows:1.A fully automatic and all EPC controlled capillary-capillary MDGC system were established.Based on SGE MDS 6890,the heart-cutting valve was replaced by a press-fit glass Y-splitter with zero dead volume.A GC controlled EPC module was used to provide three paths of gas for the middle pressure,cutting pressure and actuation of cold trap,respectively.The new system has following advantages:better inertness,less dead volume,more stable and lower cost.The great separating capability of the new system was manifested in the complete analysis of essential oil of a flue-cured tobacco.2.A fully automatic megabore-capillary MDGC with online enrichment was developed.Based on SGE MDS2000,the external controller was replaced by a GC valve box.The external needle valve for mid-split adjustment was replaced by a fused silica restrictor in GC oven.The solenoid valve for mid-split was replaced by a gas actuated on/off valve;actuating gas was shared with heart-cutting valve.The advantages of the new system include enhanced intergradations and automation.The pneumatic design is more reasonable.Selection of restrictors is easier.The cost is low.3.Innovations on MDGC methodology.By using a pressure/flow software for capillary columns,setting up procedure for constant flows for the 1^st and 2^nd columns were put forward.The procedure of calculation of restrictor was also provided.The method development of MDGC became much easier with the help of software.4.Chiral GC separation of nicotine enantiomers was optimized,for the first time, formation mechanism of R-（+）-nicotine in tobacco smoke was confirmed by experimental evidences.By using on-lined pyrolyzer-chiral MDGC/NPD,it was found that,racemization of S-（-）-nicotine reagent was highly synchronous to its thermal degradation process.By using on-lined pyrolyzer-chiral MDGC/NPD and pyrolyzer-GC/MS,it was found that,racemization of S-（-）-nicotine in tobacco was also highly synchronous to its thermal degradation process.During smoking process, thermal racemization of S-（-）-nicotine in tobacco is the main source of R-（+）-nicotine in smoke.5.A method for determination of 14 alkaloids in tobacco has been established. Different types of tobacco materials and cigarette fillers have been analyzed and the results were given.6.A method for chiral analysis of anatabine,nornicotine and anabasine in tobacco has been established.By simple solvent extraction and trifluoroacetic anhydride derivatisation,tobacco alkaloids were analyzed by chiral MDGC.The sample pretreatment is convenient and the repeatability is excellent with RSD below 1.5%.Through composite analysis of commercial tobacco,regular patterns of the enantiomeric composition in flue-cured,burley and oriental tobacco were elucidated.更多还原