【作者】 熊喜悦；

【导师】 陈波；

【作者基本信息】 湖南师范大学 ， 分析化学， 2013， 博士

【摘要】 随着高效液相色谱仪器微型化的发展,作为色谱分离的核心,色谱柱的微型化也逐渐受到人们的关注。毛细管整体柱是微柱的典型代表,由于制备方法简单、渗透性好、表面改性多样、流动相消耗少、传质效率高及分离性能好,日益受到研究者们的重视。整体柱发展至今,出现了大量不同功能的整体柱,应用范围基本覆盖所有的色谱分离模式。但是,在生物及环境等复杂样品的分离分析中,缺少拥有较高选择性和针对性的整体柱材料。基于这一现状,本文选取几种特殊的单体,分别制备了几种选择性高、针对性强的整体柱,主要内容如下：首先,我们用活性更好的3-(甲基丙烯酰氧)丙基三甲氧基硅烷(γ-MAPS)代替传统的四甲氧基硅烷(TMOS)和乙烯基三甲氧基硅烷(VTMS)组合作为前驱体,以甲基丙烯酸十二氟庚酯(DFHMA)为功能单体,在非水溶剂中(正丙醇、正辛醇和正十二醇),经一步热处理的“一锅法”合成了γ-MAPS-DFHMA杂化整体柱。详细考察了单体比例、致孔剂组成对整体柱结构的影响。研究了不同氟链的全氟羧酸和全氟磺酸化合物在γ-MAPS-DFHMA杂化整体柱上的吸附差异,发现此类含氟化合物在整体柱上吸附能力的随着氟链的增长而增强。最后以持久性有机污染物(PoPs)全氟辛酸(PFOA)和全氟辛烷磺酸(PFOS)为主要研究对象,以辛烷磺酸钠(SOS)为对照,考察了γ-MAPS-DFHMA杂化整体柱对PFOA和PFOS的吸附容量,及PFOA和PFOS在该整体柱上的富集效率。结果表明γ-MAPS-DFHMA杂化整体柱对PFOA和PFOS的吸附容量分别达到0.257和0.513μg/mg,而对SOS基本不吸附,并且γ-MAPS-DFHMA杂化整体柱可以将水溶液中微量PFOA和PFOS浓缩160倍。甲基丙烯酸酯取代的多面体低聚倍半硅氧烷(POSS-MA)是一种有机无机结合的新型纳米交联剂,日益受到研究者们的关注。本体系中我们选取氟链更长的甲基丙烯酸-1H,1H-全氟代辛酯(PDFOMA)为有机单体,POSS-MA为交联剂,采用自由基聚合的方法制备了一种机械强度高、孔结构均匀、低溶胀的POSS-PDFOMA杂化整体柱。色谱表征表明该整体柱能基于反相机理基线分离烷基苯系和苯胺类化合物。由于POSS结构中没有残余硅羟基,分离苯胺类物质时,流动相中无需添加改性剂。以乙腈水为流动相,在此整体柱上实现了一系列全氟链甲基丙烯酸酯化合物的基线分离,全氟链甲基丙烯酸酯化合物按照氟链长度从短到长依次出峰并且峰型对称,分离效果远远好于C18修饰的硅胶整体柱,这是氟氟亲和作用的结果。最后,用POSS-PDFOMA杂化整体柱在线分离全氟磺酸盐。由于流动相中无需加入铵盐,且在高有机相条件下洗脱,在质谱分析时,大大降低了离子抑制作用,获得了很好的质谱响应,为准确监测全氟磺酸盐类物质提供了很好的途径。由于POSS结构中没有残余硅羟基,且全氟单体的聚合物对不含氟的物质低吸附作用,因此我们进一步将POSS-PDFOMA杂化整体柱应用于大分子蛋白质的体积排阻色谱中。我们在原有整体柱合成体系上,通过改变三元致孔剂(甲苯、Brij58P和正十二醇)的组成比例,重新优化了POSS-PDFOMA杂化整体柱的孔结构。色谱表征结果显示过氧化氢酶(CAT)、牛血清白蛋白(BSA)、胰蛋白酶抑制剂(STI)和马脲酰组氨酰亮氨酸(HHL)等三种蛋白质和多肽在该整体柱上按照分子量从大到小的顺序先后被洗脱,说明该整体柱具有体积排阻的能力。逆体积排阻色谱结果得出该整体柱含有71%的总孔隙率和10%的中孔体积。聚乙二醇是一种生物相容性的聚合物,广泛应用在很多生物及化学领域,本体系选取四甲氧基硅烷(TMOS)和乙烯基三甲氧基硅烷(VTMS)为前驱体,聚乙二醇二丙烯酸酯(PEGDA, Mn-700)为有机功能单体,基于“一锅法”制备了PEG-硅胶杂化整体柱。相比已经报道的纯PEG基质有机聚合物整体柱,在保留其生物兼容性同时大大提高了整体柱的机械稳定性。进一步的色谱表征结果表明该整体柱具有亲水和疏水两种保留机理,在疏水作用模式下,能分离细胞色素C等5种蛋白质。多糖是一类由单糖通过糖苷键连接形成的高分子化合物,具有生物兼容性,由于结构特异性广泛应用于分离领域。本体系基于多糖与聚乙二醇的双水相体系,以葡聚糖和PEGDA为功能单体,基于自由基聚合和接枝反应建立了一种一步法合成糖基化多孔材料的新方法,制备了poly(PEGDA)接枝葡聚糖整体柱。整体柱合成过程条件温和,操作简单,PEG骨架的形成和表而接枝葡聚糖一步完成。另外,葡聚糖无需额外修饰即可直接参与反应,对葡聚糖结构没有破坏。葡聚糖本身不仅参与接枝反应,还在相分离过程起到关键作用。经过一系列系统性的考察,得到PEGDA、葡聚糖和水的三元相图及对应组合下合成的整体柱横截面形貌。结果表明只有在PEGDA、葡聚糖和水三者比例适中的条件下才能得到柱床均匀的双连续的整体结构。基于PEGDA和葡聚糖双水相接枝共聚的优化条件,分别以葡聚糖和硫酸葡聚糖为单体,制备了poly(PEGDA)接枝葡聚糖整体柱和poly(PEGDA)接枝硫酸葡聚糖整体柱。红外分析和热重分析结果表明葡聚糖和硫酸葡聚糖都是通过化学键合的方式接枝到PEG骨架上,表明该双水相接枝反应具有较好的灵活性,适合水溶性多糖的整体材料的制备。两种整体柱都能基于亲水作用分离5种核苷混合物。此外,poly(PEGDA)接枝葡聚糖整体柱还基于体积排阻色谱分离了BSA和两种多肽。更多还原

【Abstract】 With the rapid development of nanoscale chromatographic separation systems, micro-column, the heart of chromatography system, is becoming an increasing concern. Among various micro-columns, capillary monolithic columns have been received greatest attention due to easy preparation, good permeability, versatility in surface modification, low solvent consumption, high efficiency of transmission and good separation ability. In the past decades, a great number of monolithic columns with various functionality groups have been studied. However, there is an abysmal lack of monolithic columns with unique affinity or separation ability for some special analytes in environment samples or biomatrix. Based on this situation, we select several special monomers and prepare several monolithic columns, main contents are as follows:First, the traditional precursor composition (TMOS and VIMS) are replaced by y-methacryloxypropyltrimethoxysilane (y-MAPS), a monomer with higher activity. The organic-inorganic hybrid fluorous monolithic capillary column was synthesized by the improved "one-pot" approach via the polycondensation of γ-MAPS and in situ copolymerization of1H,1H,7H-dodecafluoroheptyl methacrylate (DFHMA) and vinyl group on the precondensed siloxanes through one-step thermal treatment. The pore properties and permeability could be tuned by the composition of the polymerization mixture. A series of perfluorocarboxylic acids and perfluoroalkyl sulfonates with different C-Fchains were employed to investigate the mechanism of fluorine-fluorine interaction. The results revealed that fluorine-fluorine interaction increased as the C-F chain of fluorous compounds increased. Then the adsoption capacities of y-MAPS-DFHMA hybrid monolithic column for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were examined via the online breakthrough curves of the two compounds. It was found that the adsorption capacities of the monolithic column for PFOA and PFOS were0.257and0.513μg/mg, respectively. In addition, the trace amounts of PFOA and PFOS in water samples can be successfully concentrated about160times to their original concentrations by this monolithic column.Polyhedral oligomeric silsesquioxane (POSS) is a type of cagelike silsesquioxane, which embodies a truly inorganic-organic hybrid architecture containing an inner inorganic framework made up of silicon and oxygen. A monolithic column with good mechanical stability, homogenuous porosity, low swelling and high affinity to fluorous compounds was prepared using a polyhedral oligomeric silsesquioxane (POSS) reagent as the cross-linker and pentadecafluorooctyl methacrylate (PDFOMA) as the functionality monomer. The chromatographic evaluation results showed that alkylbenzenes and phenyl amines were separated with good peak shapes on the POSS-PDFOMA hybrid monolithic column based on reversed-phase chromatography mode, respectively. A series of perfluoroalkyl methacrylates were baseline resolved on the optimized monolithic column under isocratic elution of70%acetonitrile aqueous solution. Such a resolution could not be achieved on a silica-based C18monolithic column. In addition, several perfluoroalkyl sulfonates were also baseline separated on the fluorous monolith applying0.1%(v/v) acetic acid aqueous solution containing75%acetonitrile as mobile phase without the addition of ammonium. This advantage is very significant for the LC-MS high sensitive analysis of perfluoroalkyl sulfonates because the ion suppression can be decreased effectively.Due to the combination of merits of POSS and fluorous phase with no residual silanols and low interaction with nonfluorinated compounds, the POSS-PDFOMA hybrid monolithic column was supposed to have low nonspecific interaction with biomacromolecules. The pore properties and permeability were retuned by the composition of the ternary porogenic solvent. The monolithic columns provided size separation of three proteins in the range of MWs from20000to250000in water. The pore size distributions were examined using inverse size-exclusion chromatography (ISEC) of a series of proteins and peptides covering a wide MW range. It was found that the best monolith had relatively large fractions of mesopores (10%), which is important for size-exclusion separation of peptides and proteins.A PEG-silica hybrid monolithic column was synthesized via one-pot approach using tetramethoxysilane (TMOS) and vinyl trimethoxysilane (VTMS) as precursor and polyethylene glycol diacrylate (PEGDA, Mn-700) as organic monomer. The obtained PEG-silica hybrid monolithic column owned better mechanical stability over previously reported pure PEG-based organic polymer monolithic columns. The characterization and evaluation results demonstrated that the obtained PEG-silica hybrid monolithic columns provided hydrophilic interaction as well as hydrophobic interaction. The optimized PEG-silica hybrid monolithic column provided hydrophobic interaction chromatography of five proteins.A novel, facile process was developed for the preparation of surface-glycosylated porous monolithic columns via aqueous two phase graft copolymerization of polyethylene glycol diacrylate (PEGDA) and dextran. In this method, porous poly(PEGDA) skeletons and surface glycosylation were synthesized via one-step process without perturbing the backbone structure of dextran. In addition, dextran not only took part in the graft copolymerization, but also played an important role in the phase separation process. The pore properties and skeletons could be tuned by the composition of the polymer mixtures.Ternary phase diagrams and SEM images of the corresponding monolithic columns were obtained after systematical investigations. The results exhibited that the bicontinuous porous structure could be formed by moderate proportion of the three conditions.On the basis of the optimal conditions of graft copolymerization of PEGDA and dextran, poly (PEGDA) grafted-dextran monolithic column and poly (PEGDA) grafted-dextran sulfate monolithic column were synthesized. FI-IR and thermal gravimetric analysis proved that polysaccharides were chemically bonded to the PEG skeletons. These results revealed this novel approach showed high versatility for preparation of series of surface-glycosylated porous monolithic columns with water-soluble polysacchrides. The obtained monolithic columns provided typical hydrophilic interaction chromatography of five nucleosides. In addition, poly (PEGDA) grafted-dextran monolithic column provided size-exclusion of BSA and several peptides.更多还原