【作者】 冯睿；

【导师】 陈浩；

【作者基本信息】 华中农业大学 ， 食品科学， 2010， 博士

【摘要】 毛细管电泳由于具有高效、快速、微量的特点,使其成为分析化学20世纪以来发展最快的研究领域之一。毛细管电色谱是毛细管电泳常用的六种分离模式之一,兼具电泳的高效和液相色谱的高选择性优点,成为当代色谱学发展的新方向和研究热点。色谱柱是色谱技术的心脏,而固定相是色谱柱中最关键的部分。随着现代分离技术的发展,现有的电色谱固定相难以满足日益复杂分离对象的分离要求,因此,发展新型毛细管电色谱固定相具有非常重要的意义。整体柱是采用有机或无机聚合的方法在色谱柱内进行原位聚合的连续床固定相。硅胶基质整体柱具有高的通透性和柱容量,溶剂耐受能力强,化学稳定性高等优点,但是由于硅胶基质整体中只有硅羟基,分离能力有限,可以通过柱后修饰和有机-无机杂化这两种方法能引入更多的功能基团来实现高选择性的分离。杂化法是将含有有机功能基团的硅氧烷前驱体引入溶胶-凝胶缩聚的过程中,这样就可以直接在合成硅胶基质的同时引入所需的功能基团,一步制得整体柱来满足分离的要求,通过改变各种具有不同性质前驱体的配比,可以方便地控制杂化固定相的结构特性和选择性。该方法中所形成的Si-C与整体以共价键形式结合,能克服柱后修饰的固定相水解稳定性较差的不足。超分子化学是一门研究分子间特定识别能力的新兴学科,超分子化合物所具有的主-客体识别能力为高选择性的色谱分离提供了广阔的发展前景,因而被广泛地应用于复杂物质的分离和纯化。近年来,利用两种超分子化合物的协同作用用于解决复杂样品的分离已引起关注,也有用于毛细管电色谱固定相的报道,但是用作毛细管电色谱整体柱固定相的报道并不多见。本文合成了几种含有端烯基的新型超分子液晶和液晶冠醚化合物和含有双键的离子液体,制作了含有乙烯基的杂化硅整体柱,通过双键聚合反应,将所合成的超分子化合物及离子液体键合到杂化硅整体柱表面,系统研究了其在毛细管电色谱中的分离性能,并将其应用到实际样品的分析中。主要内容如下：1.合成了含有端烯基的液晶4’-(ω-十一烯基氧)-4-联苯酚(UX)；三种含有端烯基的液晶冠醚：4-(烯丙基氧)-4’-(4’-羧基苯并15-冠-5)联苯(PCB)、4-(ω-十一烯基氧)-4’-(4’-羧基苯并15-冠-5)-2,2-二苯丙烷(UCP)和4-(ω-十一烯基氧)-4’-(4’-羧基苯并15-冠-5)联苯(UCB)。并采用熔点测定、红外光谱、拉曼光谱和质谱法对所合成的几种固定相的纯度和结构进行了表征。以四甲氧基硅烷和乙烯基三甲氧硅烷为前驱体,采用溶胶-凝胶技术制备了含有乙烯基的杂化硅胶整体柱,采用扫描电镜考察了制孔剂用量、硅烷化试剂用量和尿素用量对乙烯基杂化硅整体柱形貌的影响,进一步优化了整体柱的制备条件,经优化后制备的整体柱,采用夺汞法测定了孔径分布,通孔孔径约为3μm,分布较均匀。2.将合成的带烯基的近晶相液晶4’-(ω-十一烯基氧)-4-联苯酚(UX)用作毛细管电色谱固定液,通过用自由基聚合反应将液晶固定液修饰到带烯基的有机-无机杂化硅胶整体柱上,与未进行修饰的硅胶整体柱相比较,制备的液晶整体柱有好的选择性,萘酚、多环芳烃、酞酸酯和甾体激素得到很好的分离。同时,考察有机溶剂、溶液pH值、缓冲溶剂对分离的影响。并探讨其分离机理,提出以上分离对象选择性的改善主要是由于液晶上长链烷基的疏水作用和液晶上的羟基官能团氢键作用所致。3.通过自由基聚合将所合成的含有端烯基的液晶冠醚4-(ω-十一烯基氧)-4’-(4’-羧基苯并15-冠-5)-2,2-二苯丙烷(UCP)键合至硅胶整体柱上,首次制备了液晶冠醚UCP修饰的杂化硅基质整体柱。成功地实现了多环芳烃、苯二酚、氨基甲酸酯农药和甾体等难分离物质的分离。相比未修饰液晶冠醚的杂化硅基质整体柱,电色谱分离选择性显著提高。由于液晶冠醚冠醚上的富电子云密度的氢键作用及长链液晶基团的疏水作用的协同效应,使该柱具有高选择性和良好的分离效率。4.通过自由基聚合反应将短链液晶冠醚4-(烯丙基氧)-4’-(4’-羧基苯并15-冠-5)联苯(PCB)和长链液晶冠醚4-(ω-十一烯基氧)-4’-(4’-羧基苯并15-冠-5)联苯(UCB)交联到杂化硅整体柱上,制备了两种液晶冠醚PCB和UCB修饰的杂化硅基质整体柱。成功地实现了酞酸酯、酚类和核苷酸的分离。并与液晶修饰的整体柱(UX)以及未修饰的整体柱的分离效果进行了比较。结果表明：对于酞酸酯的分离,是由于长链的疏水作用导致；对于酚类物质的分离,氢键作用力和疏水作用都有贡献,二者的协同作用可以提高分离的效果。5.以自制的液晶冠醚修饰的杂化硅整体柱(UCB-VTMS-TMOS)为毛细管电色谱的分离柱,首次建立毛细管电色谱法分析番茄中毗虫啉和多菌灵残留的定量检测方法。对样品萃取和净化条件以及毛细管电色谱分离条件进行了优化,考察了待测样品的基质效应对定量结果的影响,采用标准加入法定量,能有效地克服基质效应,回收率令人满意。方法的检出限均低于国际食品法典规定的最大残留限量(MRL),方法快速、简便,适合于番茄中吡虫啉和多菌灵的残留分析。6.合成了含有烯丙基的离子液体采用自由基聚合反应将所合成的含有烯丙基的离子液体氯化1-烯丙基-3-甲基咪唑(1-allyl-3-methyl imidazole chloride,记作AMC),采用红外光谱和核磁共振对其结构进行表征。通过自由基聚合反应将其固定到杂化硅整体柱表面,制备了离子液体修饰的杂化硅整体柱,利用该整体柱分离了核苷酸、酚类物质和苯甲酸。与未进行修饰的整体柱相比较,分离选择性提高,究其原因,认为是碳链提供的疏水作用和咪唑环提供的氢键作用以静电作用导致。更多还原

【Abstract】 Capillary electrophoresis is a type of micro-separation methods that separates samples by their various properties using capillary as the separation channel and high-voltage electric fields as driving force. For the features of its efficient, fast, and trace quantity, capillary electrophoresis is becoming to the fastest growing areas of analytical chemistry. As one of six kinds of separation modes of CE, capillary electrochromatography is a hybrid technique that combines the high efficiency of capillary electrophoresis and good selectivity of high performance liquid chromatography, which is the new aspect and have been focus of chromatography development. Chromatography column is the heart of chromatography technique, while stationary phase is the key component of chromatography column. However, the stationary phases existed could not meet the demand of analysis as the samples are becoming more complicated, therefore, the development of new stationary phases for CEC to address this issue is of great significance.Monolithic column is a kind of chromatography column which can be prepared by sol-gel and in-situ free radical polymerization technology. Silica based monolith exhibits high permeability and column capacity, excellent solvent tolerance ability, and mechanical stability, however, there are only siloxane bonds in this kind of monolithic column which is restricted for further use by its poor hydrolytic stability, which could be improved by modification and organic-inorganic hybrid. Hybrid silica monolith was synthesized through a "one pot" approach by inserting a functional group and content with the separation demand. The characteristic of structure and selectivity of the stationary phase could be controlled by changing the ratio of the precursor. The Si-C bond and monolith were combined by covalent bonds, which could overcome the disadvantage of poor stability of the stationary phase modified after column.Supramolecular chemistry is a kind of emerging subject, which deals with the specific recognitions between molecules. The host-guest interactions, which are exerted by supramolecular compounds, can provide a promising prospect for chromatographic separations with high selectivity. They have been widely used for purification and separation of complicated mixtures. Nowadays, it has been attracted considerable attentions that the synergistic reaction of two kind supramolecular compounds on the separation of complicated samples, and the use as stationary phase on CEC has been reported, while it has received scant attention on CEC monolithic columns. Several kinds of novel supramolecular liquid crystal and liquid crystal crown ether with terminal vinyl were synthesized, and vinyl hybrid silica monolithic column was prepared in this paper, then the supramolecular was bonded to the monolith by free radical polymerization reaction. The electrochromtographic performance of the column was systematically studied, and was used in real samples. The main points of this dissertation are listed as follows:1. Terminal-vinyl supramolecular liquid crystal 4’-(ω-undeceny-1-lyoxy)-4-xenol (UX), liquid crystal crown ether 4-allyloxy -4’-(4’-carboxylbenzo 15-crown-5)-biphenyl (PCB),2-[4-(ω-undeceny-1-yloxy)-phenyl]-2-[4’-(4’- carboxybenzo-15-crown-5)-phenyl] propane (UCP) and 4- (ω-undecenyl-1-lyoxy)-4’-(4’-carboxylbenzo 15-crown-5)-biphenyl(UCB) were synthesized, which could be bonded to vinyl hybrid silica monolithic column. Melting point test, infrared spectrum, Raman spectrum and mass spectrum were used to confirm the structure and purity of the compounds. Vinyl hybrid silica monolith was prepared, the condition such as the dosage of porogenic agent, silylating reagent and urea were investigated. After optimizing preparation conditions, the pore diameter was measured by mercury porosimetry, and the median pore diameter was around 3μm.2. The terminal-vinyl liquid crystal 4’-(ω- undeceny-1-lyoxy)-4-xenol (UX) was used to modify terminal-vinyl organic-inorganic hybrid silica monolithic column by free radical polymerization procedure. Naphthol, PAHs, phthalate ester and steroids were successfully separated on the column and the separation effects were compared with unmodified column. The separation conditions including organic solvent, pH, and buffer agent on the effect of separation were investigated. The mechanism was inferred to hydrophobic interaction supplied by alkyl chain and hydrogen bonding supplied by hydroxide on liquid crystal.3. The terminal-vinyl liquid crystal crown ether 2-[4-(ω-undeceny-1-yloxy)-phenyl]-2-[4’-(4’-carboxybenzo-15-crown-5)-phenyl] propane (UCP) was firstly used to modify hybrid silica-based monolithic column possessing vinyl ligands by free radical polymerization procedure. Polycyclic aromatic hydrocarbons, benzenediols, carbamate pesticides and steroids, were successfully separated on the column. Compared with unmodified monolithic column, the selectivity was observably improved, which was caused by the high electron cloud hydrogen bonding on crown ether and hydrophobic interaction on liquid crystal chains.4. Two terminal-vinyl liquid crystal crown ethers 4-allyloxy -4’-(4’-carboxylbenzo 15-crown-5)-biphenyl (PCB) and 4-(ω-undecenyl-l-lyoxy)-4’-(4’-carboxylbenzo 15-crown-5)-biphenyl (UCB) with different alkyl groups were introduced to modify hybrid silica monolithic columns possessing vinyl ligands. Phthalate esters, phenols and nucleotide acids, were successfully separated on the column and the results were compared with UX modified column and unmodified column. The results indicated that the hydrophobic interaction played an important role on UCB column and UX column, the separation effect on phthalate esters was better than PCB column, while the synergy of hydrogen bonding interaction and hydrophobic interaction makes the separation on phenols better.5. Determination of imidacloprid and carbendazim residues in tomato was performed using capillary electrochromatography with a terminal-vinyl organic-inorganic hybrid silica monolithic column modified by liquid crystalline crown ether (UCB-VTMS-TMOS). Standard addition method was employed to overcome the matrix effects which were thoroughly investigated in the article. Satisfactory recoveries were obtained and the limits of detection were both below the MRL values stipulated by CAC. The result showed the method developed was applicable to the determination of imidacloprid and carbendazim residues in tomato with rapid analysis and simplicity.6. A kind of ionic liquid,1-allyl-3-methyl imidazole chloride (AMC) was synthesized; the structure was examined by infrared spectrum and nuclear magnetic resonance and was used to modify the vinyl hybrid silica monolith by free radical polymerization procedure. Nucleotide acids, phenols and benzoic acid compounds were separated on the column and the separation mechanism was discussed. Compared with unmodified column, the selectivity improved, which was believed to the hydrophobic interaction on carbon chain, hydrogen bonding interaction and electrostatic interaction on imidazole ring.更多还原