【作者】 王博妮；

【导师】 曹玉华；

【作者基本信息】 江南大学 ， 分析化学， 2012， 硕士

【摘要】 毛细管电动色谱(EKC)是毛细管电泳的一种分离模式,因其采用胶束、微乳等作为假固定相,将毛细管电泳的分析对象从荷电物质扩展到中性、脂溶性物质。目前已有新型表面活性剂胶束如生物表面活性剂和双子表面活性剂、脂质体、离聚物等作为假固定相用于EKC的分离分析中,但未见把两亲性聚合物自组装后的胶束作为假固定相应用于毛细管电泳中的文献报道。本论文首次尝试将两亲性无规聚合物P(MMA-co-MAA)自组装后的胶束应用于毛细管电泳,一方面是解决传统表面活性剂SDS形成的胶束应用于MEKC对于高亲脂性物质分离选择性的局限;另一方面是解决经典微乳体系中因高浓度表面活性剂造成的焦耳热过大,时间过长等问题。本论文的主要研究共有三个部分:1.用单体甲基丙烯酸甲酯(MMA)和甲基丙烯酸(MAA)、溶剂1,4-二氧六环及引发剂偶氮二异丁腈(AIBN)无规共聚,通过改变单体投料的摩尔比和改变引发剂的百分含量,分别合成了一系列聚合物链上MMA和MAA配比不同和分子量不同的无规共聚物甲基丙烯酸甲酯甲基丙烯酸(P(MMA-co-MAA))。用傅里叶红外光谱(FTIR)和核磁共振仪(HNMR)表征了合成的产物P(MMA-co-MAA)的结构,结果表明无规共聚的聚合物链上基团MMA和MAA比例与投料单体摩尔比基本符合;凝胶渗透色谱(GPC)测定了P(MMA-co-MAA)分子质量及其分布,实验结果说明采用改变引发剂含量来控制聚合物的分子量,测得其分子量在2万到10万之间且聚合物的分子量分布较窄。2.利用两亲性聚合物的特性,发明了一种快速、简单、绿色的制备聚合物胶束的方法。制备两亲性无规聚合物P(MMA-co-MAA)胶束的方法是把一定质量的该聚合物溶解于碱性溶液(本实验用氢氧化钠溶液),并根据实验需要调节其溶液的pH值。通过TEM和DLS及Zeta电位分别表征了胶束的形貌、大小及表面电荷密度,实验考察了聚合物浓度、溶液pH、聚合物不同基团摩尔配比及聚合物分子量对胶束的影响,研究结果表明聚合物浓度主要影响胶束的形貌,共聚物不同基团摩尔配比主要影响胶束的粒径,而胶束表面的电荷密度主要受溶液的pH值影响。当聚合物的单体MMA:MAA投料摩尔比为6:4,Mn=88924,Mw=104213,Mw/Mn=1.17时,浓度为0.048 mmol/L,溶液pH为9.2时,得到大小均一的球形胶束,优化得到的此聚合物胶束作为假固定相应用于MEKC中。3.首次采用两亲性无规聚合物P(MMA-co-MAA)胶束溶液成功应用于胶束毛细管电动色谱快速分离了化妆品中三种结构相似的皮质类激素氢化可的松、泼尼松龙和泼尼松。实验考察了聚合物浓度、溶液pH、聚合物基团配比、聚合物分子量、分离条件(如温度、电压等)对分离效果的影响。其体系的最佳分离条件为:聚合物单体MMA与MAA的投料比为6:4,聚合物浓度为0.048 mmol/L,硼砂缓冲液(100 mmol/L,pH 9.2);电泳的最佳分离条件:分离电压20 kV,分离温度20℃,电动进样3 s/20 kV条件时,氢化可的松、泼尼松龙和泼尼松可在7.4 min内成功分离。三种激素的线性范围是2~100 mg/L,且重复7次进样,迁移时间RSD小于0.17%,迁移峰面积RSD小于3.7%,检出限依次为0.63、0.94和1.2 mg/L (S/N=3)。该法用于化妆品样品中糖皮质激素的测定,样品的平均回收率在97.7%和113%之间。相对于传统的胶束体系、离子液体修饰的胶束体系和经典的微乳体系,聚合物胶束用于EKC,分析速度更快,分离效果更好和选择性更多。从分析物流出顺序,得出两亲性无规聚合物自组装胶束应用于EKC的分离机制是反相色谱机制。更多还原

【Abstract】 Electrokinetic chromatography (EKC) is one mode of capillary electrophoresis (CE). Based on pseudostationary phase (PSP), such as micelle and microemulsion, EKC could extend analytes from charged substances to neutral, water-insoluble molecules. Recently, a large number of novel surfactants such as biosurfactant and gemini surfactant, dendrimers, liposomes, vesicles, ionic polymers have been used as PSP in EKC. However, to my knowledge, self-assembly of amphiphilic polymer micelles as PSP in MEKC has not been reported. The present work firstly used polymeric micelle as PSP in CE to attempt to overcome difficulties in MEKC or MEEKC. On the one hand, conventional SDS micelles as PSP in MEKC the is limited to separate highly lipophilic substances.On the other hand, high concentration of ionic surfactant to form microemulsion results in high joule heating, longer analysis time. The thesis mainly included the following three parts.1. A series of random copolymers poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) with different feed monomer ratio and different molecular weight were synthesized by radical polymerization, using methyl methacrylate (MMA) and methacrylic acid (MAA) as monomers, 2,2-Azobis (isobutyronitrile) (AIBN) as initiator, 1,4-dioxane as solvent. The random copolymers P(MMA-co-MAA) were characterized by means of FTIR, 1H NMR and Gel Permeation Chromatography (GPC). The results show that the proportion of the MMA and MAA groups on the chain of random copolymer is similar as the feed monomer molar ratio and the molecular weight of the polymer was controlled by changing the initiator content, its molecular weight is between 20000 and100000 and distribution was narrow.2. A fast, simple and green method of the preparation of polymeric micelles has been invented, according to the characteristics of the amphiphilic polymer. The micelle of amphiphilic random polymer P (MMA-co-MAA) is prepared by dissolving certain quantity of the polymer in alkaline solution (sodium hydroxide solution used in this experiment) and the pH is adjusted in light of the experiment. The aqueous self-assembly of the random polymers were investigated by using transmission electron microscopy (TEM), dynamic laser light scattering (DLS) and Zeta potential. The effects of concentration of polymer, pH of the running buffer, molecular weight of polymer and different feed monomer ratio of MMA and MAA were investigated. Results showed the shape and the size of polymeric micelle were mainly influenced by the concentration of polymer and different feed monomer ratio of MMA and MAA, respectively. The Zeta potential of micelle was controlled by pH of the running buffer. At the concentration of 0.048 mmol/L, feed monomer ratio of 6:4 (MMA to MAA) and pH 9.2, the polymeric micelles were of monodispersity and perfect spheres. The optimum conditions of preparation polymeric micelle were utilization of the polymeric micelle as a pseudostationary phase to improve MEKC performance.3. The polymeric micelle with amphiphilic random copolymer P (MMA-co-MAA) via neutralization in aqueous medium was firstly applied as a pseudostationary phase (PSP) in electrokinetic chromatography (EKC) in the present work. Three structurally similar corticosteroids namely hydrocortisone, prednisolone and prednisone were separated with EKC using polymeric micelle as PSP to assess the separation performance. The concentration of polymer, pH of the running buffer, molecular weight of polymer and different feed monomer ratio of MMA to MAA on EKC performances have been investigated, and the optimum condition is at the concentration polymer( MMA:MAA 6:4 and Mn=88924, Mw=104213, Mw/Mn=1.17) of 0.048 mmol/L and pH 9.2. With separation voltage of 20 kV, electrokinetic injection of 3s/20 kV and capillary temperature of 20℃, prednisone, hydrocortisone and prednisolone were baseline separated within 7.4 min. The RSDs of migration time for three analytes were all less than 0.17% and peak area were less than 3.7% (n=7). Excellent linearity was obtained ranged from 2 to 100 mg/L, the detection limits based on ratio of signal to noise of 3 were 0.63, 0.94 and 1.2 mg/L for three analytes respectively. Compared with typical MEKC, MEEKC and MEKC modified with IL ([Bmim]BF4), the developed method was more rapid, efficient and higher selective. The separation mechanism using polymeric micelle as PSP was reverse-phase interaction. The method has been applied to determination of the three corticosteroids in actual cosmetic samples, the recoveries of three analytes were between 97.7% and 113%.更多还原