【作者】 李平；

【导师】 周天舒；

【作者基本信息】 华东师范大学 ， 环境科学， 2012， 硕士

【摘要】 毛细管电泳(Capillary Electrophoresis, CE)以高压电场为驱动力,以毛细管为分离通道,依据样品中各组分之间淌度及分配系数的差异来实现高效、快速分离的新型液相分离技术。由于其具有分离效率高、分析速度快、检测灵敏度高、样品用量少等优点,近年来在生命科学、环境科学、临床医学、化学等各得到广泛应用。环境问题对人类日常生活的影响日益明显,需要有效的分析测试方法对各种环境污染物进行准确分析,为确定相应的解决方案提供科学的依据。毛细管电泳电化学方法(CE-ED)具有灵敏度高、选择性好等特点,能满足各种环境污染物的痕量的检测,在环境分析中具有很好的应用前景。随着化学修饰电极和毛细管在线预富集技术的发展,进一步提高了毛细管电泳-电化学检测方法的选择性、灵敏度和分离效率。一直以来,电化学检测法(ED)由于其快速、便捷、灵敏度高等优势备受分析家的青睐。近年来,由于化学修饰电极的广泛使用,电化学检测法的应用范围也得到了进一步的拓展。本论文以毛细管电泳分离技术和电化学检测技术为基础,结合毛细管在线富集技术和化学修饰电极技术,以雌激素、酚类农药和三聚氰胺为研究对象,建立了用于快速、灵敏、准确检测的毛细管电泳检测及电化学检测的方法。全文共分一下四个部分：1.绪论(第一章)该部分首先介绍了环境污染的分类和危害；其次介绍了目前主要的检测方法；最后重点介绍了毛细管电泳检测技术及电化学检测技术在环境分析中的应用。2.毛细管电泳在线富集方法用于水环境中的雌激素的测定研究(第二章)雌激素由于其具有内分泌干扰效应,即使在环境中含量很低也会通过协同或拮抗作用模仿内源雌激素、改变内源雌激素的合成或代谢途径、改变内源雌激素受体的浓度水平等途径来产生内分泌干扰效应,影响生物的生长繁殖。因此,必须建立一种可靠、灵敏、快速的方法对不同环境样品中的雌激素进行测定。本章中,首次将毛细管电泳乙腈-盐在线堆积技术与铜电极电化学检测法相结合,同时分离检测雌酮、17β-雌二醇和雌三醇等三种雌激素。实验表明乙腈-盐在线堆积能有效的提高毛细管电泳电化学检测的灵敏度。在最佳实验条件下,三种雌激素在0.06mol/L的NaOH运行液中14分钟内得到分离,在0.2到10μmol/L范围内电流响应与浓度呈良好的线性关系,相关系数大于0.9993。通过5%的乙腈和0.5%的NaCl进行乙腈-盐堆积,雌三醇、雌二醇和雌酮的最低检出限分别为8.9×10-8、6.7×10-8和1.1×10-7mol/L(S/N=3)。该方法成功用于对多种环境水样中雌激素的测定,发现自来水厂的源头水、养鱼场的废水和河水中均含有一定量的雌激素,样品的回收率在90.8%到108.9%之间,RSD小于4.69%,方法具有良好的应用前景。3.基于MWCNTs-COOH@Pdop纳米修饰电极的毛细管电泳电化学方法对酚类农药的测定研究(第三章)由于农药的大量使用,酚类农药以农药残留的形式存在于环境中,并可以通过呼吸、皮肤接触及饮食等各种形式进入生物体内,对人和其他生物的健康造成严重的危害。因此有必要建立一种快速、准确、灵敏的方法用于检测环境中的酚类农药残留。本章中,首次合成了可在水溶液中稳定分散的聚多巴胺包裹的羧基化多壁碳纳米管,将其修饰的碳圆盘电极作为工作电极,采用毛细管区带电泳-电化学检测法(CZE-AD)对四种酚类农药2,3,5-三甲基苯酚、2-氯-4,5-二甲基苯酚、双氯酚和六氯酚等进行分析测定。实验表明,聚多巴胺包裹的羧基化碳纳米管对四种酚类农药具有有效的电催化作用。在最佳的实验条件下,四种酚类农药在0.01mol/L Na2CO3-NaHCO3缓冲溶液(pH9.7)中可在480s内得到分离,碳圆盘电极在0.75mg/mL聚多巴胺包裹羧基化碳纳米管的水溶液中浸泡10分钟得到的修饰电极检测四种酚类农药时电流响应是最大的。检出限分别为4.6μg/L、2.7μg/L、9.2μg/L和69.2μg/L(S/N=3)。该方法成功用于青菜和苹果表面的酚类农药残留测定,发现青菜和苹果表面均有一定量的酚类农药残留。4.基于FDU-15-Pt/PDDA/GCE修饰电极的快速检测牛奶中三聚氰胺的电化学方法研究(第四章)用于工业生产的三聚氰胺由于其价格便宜且含氮量高,一些不法商家将其添加在人和宠物的食品中造成蛋白质含量高的假象。三聚氰胺在肾脏内形成结石,危害人类和其他动物的生命安全。因此,食品中三聚氰胺的快速、准确检测成为当前高度重视和亟待解决的问题。在本章节中,采用层层组装的方法制备了FDU-15-Pt/PDDA/GCE修饰电极,建立了对三聚氰胺灵敏、快速的电化学检测方法。利用循环伏安、示差脉冲伏安、交流阻抗和透射电镜对修饰电极的电化学行为及物理形态等进行了表征。研究表明,通过恒电位富集后,在含有1mmol/L K3[Fe(CN)6]及0.5mmol/L KCl的磷酸盐(pH6.5)缓冲溶液中,电化学探针[Fe(CN)6]3-/4-还原峰电流的减小量与三聚氰胺的浓度在一定范围内呈良好的线性关系。在最优条件下,采用示差脉冲伏安法对三聚氰胺进行了检测,线性范围为5.0×10-9～1.4×10-7mol/L相关性系数达到0.991,最低检出限达到1.7×10-9mol/L。该方法可用于对乳制品或其他食品中三聚氰胺的测定,具有很好的应用前景。更多还原

【Abstract】 Capillary electrophoresis (CE) is a combination of classical electrophoresis technology and modern microcolumn technology. The separation principle is based on the phenomena that ionized molecules of different mass or/and charge will travel with different velocities through a fused silica capillary under the force of a high-voltage electric field. Recently, CE has been widely used in different fields, such as life science, agriculture, food, clinical medicine, environmental analysis and chemistry, because of its powerful capability for the analysis of complex samples due to its high separation speed and efficiency, low volume sample, the relatively simple instrument and low running costs. Environmental issues have more and more serious influence on our daily life, and this requires more effective environmental pollutants analysis and detection methods to privide a scientific basis for the corresponding solutions.Capillary Electrophoresis-Electrochemical Detection (CE-ED) has the advantage of high sensitivity and good selectivity. It can meet all kinds of environmental pollutants traces of detection, and has very good application prospects in environmental analysis.As the devolpment of stcacking online and chemically modified electrodes, the CE will have more great potential in the application of environmental analysis.The characteristic of high sensitivity and convenience in electrochemical detection (ED) makes it very popular in analysts for a long time. Recently, the chemically modified electrodes have been widely concerned, which broadened the ED application prospect in food, environmental monitoring and military fields.This dissertation is based on the capillary electrophoresis and electrochemical detection for determination of estrogens, phenol pesticides and melamine by coupled with stacking online and chemically modified electeodes.The dissertation includes four chapters:Chapter1. IntroductionIn this chapter, the harm and the analysis technologies of environmental pollutants were outline. The applictions of capillary electrophoresis and electrochemical detection in nvironmental analysis were highlighted.Chapter2. Stacking and simultaneous separation of estrogens in water samples by capillary electrophoresis with electrochemical detectionA rapid and sensitive method based on acetonitrile-salt stacking in capillary electrophoresis with eletrochemical detection at copper disk electrode was developed for the simultaneous separation and determination of three estrogens:estrone,17β-estradiol and estriol. The effects of several important factors that influence the separation and detection were investigated. Under the optimum conditions, the estrogens could be separated in0.06mol/L sodium hydroxide solution within14min. With acetonitrile-salt stacking by5%acetonitrile and0.5%NaCl, a good linear response was obtained for three estrogens from0.2to10μmol/L, with correlation coefficients higher than0.9993. And the detection limits of them were8.9×10-8,6.7×10-8and1.1×10-7mol/L (S/N=3) for estriol,17β-estradiol and estrone, respectively. This method was successfully employed to analyze different water samples from waterworks, tap water fishpond, and river samples with recoveries in the range of90.8-108.9%, and RSDs less than4.69%. The satisfied results demonstrated that this method was of convenient preparation, high sensitivity and good repeatability, which could be applied to the rapid determination of environmental water samples.Chapter3. Determination of four phenol pesticides with MWCNTs-COOH@Pdop hybrid nanocomposite by capillary electrophoresis with electrochemical detectionIn this article, the MWCNTs-COOH@Pdop hybrid nanocomposite was synthesized. The carbon disk electrode modified with MWCNTs-COOH@Pdop was used in CE with electrochemical detection system for the simultaneous determination of four types of phenol pesticides, including2,3,5-trimethylphenol (TMP),2-chloro-4,5-dimethylphenol (CDMP), dichlorophene (DCP) and hexachlorophene (HCP). Compared with the bare carbon electrode, the MWCNTs-COOH@Pdop modified electrode greatly improved the sensitivity at a relatively positive detection potential due to its excellent electrocatalytic activities, high conductivity, and large effective surface area. The effects of several important factors were investigated. Under the optimum condition, TMP, CDMP, DCP and HCP could be separated in10mmol/L Na2CO3-NaHCO3buffer (pH9.7) within480s. The detection limits of them were4.6μg/L、2.7μg/L、9.2μg/L and69.2μg/L (S/N=3), respectively. And this method was applied directly for the determination of TMP, CDMP, DCP and HCP in fruits and vegetables samples with satisfactory results.Chapter4. Electrochemical determination of melamine based on FDU-15-Pt/PDDA/GCE in MilkA novel and simple electrochemical method for determination of melamine was developed based on the composite films of FDU-15-Pt/PDD A modified glassy carbon electrode (GCE). Results of cyclic voltammetries (CV), differential pulse voltammetries (DPV), electrochemical impedance spectrometry (EIS) and transmission electron microscopy (TEM) proved that melamine might interact with FDU-15-Pt mainly through electrostatic and hydrogen-bonding interactions. The electrochemical probe of [Fe(CN)6]3-/4-was used to investigate the interactions between FDU-15-Pt and melamine. The reduction of redox peak currents of [Fe(CN)6]3-4-were linear with the concentration of melamine in the range of5.0×10-9-1.4×10-7mol/L with a linear coefficiency of0.991. The detection limit was1.7×10-9mol/L. This proposed procedure has been successfully used for the determination of melamine in milk products.更多还原