【作者】 李玮；

【导师】 孔继烈；

【作者基本信息】 复旦大学 ， 分析化学， 2008， 博士

【摘要】 现代社会环境中的重金属污染物,尤其是铅的污染问题日益引起人们的关注,环境及人体中铅的检测方法研究广泛开展。铅是环境中广泛存在并具有很强毒性的重金属离子,随着现代工业和交通的高速发展,环境铅污染日趋严重,已经成为影响人类,尤其是儿童健康的一个重要社会问题。研究证实:血铅水平超过100μg/L将影响儿童的生长发育,特别是损害儿童的神经发育,影响儿童的智力和行为。目前常用的血铅测定方法包括双硫腙络合比色法、原子吸收光谱法、原子发射光谱法等。所有这些方法都存在分析成本昂贵、操作步骤繁琐、分析时间长等缺点。与此相比电化学方法,以其低成本和高灵敏度的优点,成为包括铅在内的重金属离子检测的优势方法。经由各种途径制备的化学修饰电极,通过可控的方法对电极表面的分子剪裁,可按意图给电极预定功能,以便在其上有选择地进行所期望的反应,在分子水平上实现了电极功能的设计。化学修饰电极是当前电化学、电分析化学方面十分活跃的研究领域。这种修饰电极包括了对电极界面区的化学改变,因此它所呈现的性质与电极材料本身任何表面上的性质不同。自1975年化学修饰电极问世以来,为化学和相关边缘学科开拓了一个创新的和充满希望的广阔研究领域。为了提高分析检测的灵敏度,满足实时现场分析的需要,降低分析成本及样品需要量,如何实现整个分析检测装置的微型化进而得到有效的化学生物传感器已成为当前分析化学微型化与集成化研究的重要发展前沿之一。基于化学修饰电极构建的传感器系统已在自然及生命科学领域得到了广泛的应用,成为一个常用的研究解决科研及实际问题的有效工具。而集成化、微型化也已成为研究的热点。通过分析系统的微型化,可以有效减少样品和试剂的需要量,降低分析成本及能耗,同时还可以提高检测分析的灵敏度,增加检测通量。引起了广大研究工作者的关注。本论文正是基于以上的研究背景,围绕如何能够将基于新型化学修饰电极体系建立的化学生物传感器应用于实际样品分析,使实验室的研究工作最终能够与大众的现实生活要求相接轨这一目标,开展了工作。着重建立更加灵敏、简便、准确的重金属Pb（Ⅱ）的定量分析方法,以期能将所建立的分析方法实际推广到血铅和环境铅离子的检测中。因此,本课题具有重大的理论和实际意义。本论文共分为六个部分:第一章首先介绍了铅的毒性及其对人体的危害,总结了铅离子的实际检测手段。再次,介绍了化学修饰电极的概况,列举了其主要的制备方法及在电分析化学领域内的应用。最后,提出了本论文的实验思路,对本论文的研究思路及创新点进行了概述。指出了该课题的理论和实际意义。第二章构建了一种可用于血铅检测的集成型薄膜电极。使用CAD技术设计了集成型三电极体系的模版。利用蒸镀的方法,将电化学传感器技术、现代印刷技术与微机械加工技术相结合,研制出可批量生产的一体化三电极体系。分别考察了导电银胶与氯化银粉末混合涂布的Ag/AgCl电极与在金膜基底上电镀制作的Ag/AgCl参比电极,最终在金膜表面制得了稳定的Ag/AgCl参比电极。从而发展得到了将金膜工作电极、Ag/AgCl参比电极、碳印刷油墨对电极集成于一体的三电极集成体系。为血铅检测的集成化、微型化提供了可能。随后采用共沉积镀汞的方法对标样中的Pb（Ⅱ）进行检测,分别考察了沉积时间、沉积电位、后溶出时间对实验结果的影响,并对其实验条件进行优化,分别考察电极的稳定性和可靠性。第三章在第二章工作的基础上利用基于成熟技术制备的薄膜电极进一步构建快速血铅分析系统。采用微分脉冲阳极溶出伏安法,通过原位镀汞,将mL级电解池体系下的反应降至50μL的微量体系下进行,在3min时间内就可测出μg/dL水平的微量血铅。减少了采血量和大比例稀释血样引起的系统误差;同时所采用的一次性电极即避免了传统电极重复使用清洗所造成的额外工作量,又避免了电极反复使用可能造成的血液样品之间的交叉污染。在pH=1.1的溶液体系中,检测限达到了1.2μg/dL,铅离子在1.2～70μg/dL的浓度范围内呈现良好的线性关系。通过对大量实验数据的分析整理,在严格控制集成三电极体系的制备条件下,得到对于此血铅快速分析系统具有普遍适用性的经验公式Y=9.726E-8+X*9.959E-8（线性相关系数为0.998）。此血铅快速分析系统具有快速、准确,低成本等特点,能够达到现场实时检测的要求。进一步的工作针对蒸镀金膜电极本身所存在的缺陷造成的筛选率较高的问题,对三电极体系进行改进,以碳印刷油墨作为工作电极。实验结果表明,该电极体系同样具有良好的稳定性和可靠性。第四章合成巯基修饰的β-环糊精（6-（2-mercaptoethylamino）-6-deoxy-β-cyclodextrin,MEA-β-CD）,在金电极表面构建了一层性能稳定的巯基化合物自组装膜（self-assembled monolayer,SAM）。通过电化学手段对自组装电极表面进行了表征,进而得到了一种可用于无汞条件下对Pb（Ⅱ）进行检测的新型膜修饰电极。通过对实验条件的优化,发现通过增加正电位下的后溶出过程,能够很好的实现电极的再生。该修饰电极相对于其他干扰离子:Cu（Ⅱ）、Cd（Ⅱ）、Co（Ⅱ）、Ni（Ⅱ）、Zn（Ⅱ）和Cr（Ⅱ）显示出了对Pb（Ⅱ）极高的选择性。实验以酸性溶液HClO₄作为媒介,采用微分脉冲溶出伏安法。检出限0.71×10^-8M（以3倍信噪比计算）,这与传统的基于汞的铅离子检测手段相比非常接近,而又不会对健康与环境造成危害。在1.7×10^-8M到9.3×10^-7M的浓度范围内保持线性关系,大大优于文献所报道的以涂布法等制备的环糊精修饰玻碳电极的结果。该修饰电极为创造高灵敏度高选择性的无汞测铅传感器提出了一个新的途径。将此电极应用于实际血液样品的检测,其结果与ICP-AES方法的结果相一致。第五章,利用杂环类化合物修饰电极对铅离子的检测进行了初步探讨。在本章中,讨论了杂环类化合物噻吩、吡咯共聚,及桑色素在电极表面聚合制备检测痕量铅离子的几种新型膜修饰电极。文章共分二节。分别讨论了吡咯、噻吩单体共聚测铅和桑色素体系中的铅离子检测。杂环类化合物聚合修饰电极在无汞的条件下,对铅离子各自产生了电化学响应信号,并且呈现一定的线性关系。推测为杂环聚合物中的氮、硫、氧原子的存在,与溶液中的Pb（Ⅱ）存在一定的螯合作用,但具体的作用机理仍有待讨论。第六章首先对论文的工作进行了全面的总结,客观地评价了所取得的研究成果,同时指出了研究中存在的一些不足。并在前面几章的工作基础上,在方法学上提出了可进一步深入的方向,提出了后续工作的目标和研究路线。更多还原

【Abstract】 Heavy metal pollutants in the environment, especially the lead pollution problem, have been a cause of concern. The lead in the environment and human lead in the detection method extensively carried out. Lead is widespread in the environment and becoming a kind of highly toxic heavy metal ions. With the rapid development of modern industrial and transport, the environmental lead pollution has become a major problem affect health of human, especially for the children. It has been proved that the blood lead levels exceeding 100μ/ L will have an impact on children’ s growth and development, especially damage to the neural development of children, affecting children’s mental and behavior. The commonly methods for determination of blood lead include dithizone colorimetry, atomic absorption spectrometry and atomic emission spectrometry. All of these analysis methods have problems such as costly, cumbersome steps and taking long time. Compared with those methods, the electrochemical method has the advantages of low-cost and high sensitivity, which make the electrochemical method become a good choice for heavy metals detection, especially for lead.Chemically modified electrodes were prepared through various means. Controlled by the method of molecular tailoring of the electrode surface, according to the intent of the function of electrode is scheduled to have its choice to carry out the desired reaction at the molecular level to achieve an electrode function design. The current electrochemical and chemical analysis have very active research field. This modified electrode has a different character on the electrode interface with the nature. Since 1975, with the advent of chemically modified electrodes for the chemical and related interdisciplinary pioneering, an innovative and broad research field has been promised. In order to increase the sensitivity of detection, to meet the needs of real-time scene analysis, reduce costs and sample analysis requirements, the analysis of how to achieve the miniaturization of devices which are effectively chemical and biological sensors have become the important part for the miniaturization of chemical analysis and integration of the research. Based on chemically modified electrode, the sensor system has been constructed in the natural and life sciences fields and has been widely used as an effective tool for common research. The integrated and micro-electrodes have also become a hot research part. Through micro-analysis system, it can be effective in reducing the sample and reagent requirements, and reduce the cost of energy, improve the monitoring and analysis of the sensitivity, increase throughput detection.This paper is based on the above research background, focusing on how micro-analysis system can be chemically modified electrodes and the new system applied to the actual analysis of samples, laboratory research work can ultimately live with the reality of public convergence requirements of this goal, in work, with emphasis on the establishment of a more sensitive, simple and accurate heavy metals Pb （II） quantitative analysis method can be established with a view to the promotion of practical methods and the environment to lead the detection of lead ions. Therefore, this issue is of great theoretical and practical significance.This dissertation has great original and frontier innovation and includes six chapters, which are introduced separately as follows:In chapter one, we focus on the toxicity of lead on the human body, summed up the actual testing method for lead ion at first. Second, on the profile of chemically modified electrodes, we list the main preparation methods and the applications in the field of analytical chemistry. Finally, the experimental ideas of this paper and innovative ideas outlined points are pointed out.In chapter two, a blood lead testing integrated thin film electrode had been used. The CAD technology has been used to design the templates for integrated three-electrode system. With the evaporation method, electrochemical sensor technology, modern printing technology and micro-machining technology, the mass-produced integrated three-electrode system can be developed. The system had stable on the Ag/AgCl reference electrode, which was chosen out between the mixtures of Ag/AgCl electrodes and electroplating the Ag/AgCl reference electrode on the basal membrane, which makes it possible for the blood lead being tested on the integration of micro-electrode. Then we use the mercury deposition method for detection of Pb （II）, respectively inspected the deposition, deposition potential, the time after the dissolution of the experimental results, and its optimized experimental conditions.In chapter three, a novel fast system based on the integrated film electrodes was created. The resulting system was successfully applied in the detection of blood lead, by means of differential pulse anodic stripping voltammetry in tiny amount of volume,～50μL, co-deposited with Hg without removal of oxygen. Under the optimum conditions, the peak current was linear to Pb²⁺ concentration from 1.2 to 70μg/dL, and detection limit was 1.2/μg/dL. Blood lead was detected with calibration curve, Y = 9. 726E-8 + X*9. 959E-8（R=0. 998）. Compared with other methods reported, this method was more rapid, low-cost and could meet the requirement of real-time analysis.In chapter four, a self-assembled monolayer （SAM） of thiolatedβ-cyclodextrin （6-（2-mercaptoethylamino）-6-deoxy-β-cyclodextrin, MEA-β- CD） on a gold electrode （MCGE） was prepared. Mercury-free sensors for lead (Pb²⁺) assay based on MCGE have been developed. The analysis of Pb using MCGE-based adsorptive stripping voltammetry （ASV） includes two steps. Pb²⁺ ions are firstly adsorbed on electrode surface in a Pb²⁺ solution （5mL） during a preconcentration step, followed by a measurement step using acidic solution as medium for stripping voltammetry. Due to the strong covalent bonding of the functional groups, the MCGE-based sensors with a built-in three electrode system can be reused for tens of measurements with minimal degradation, enabling the establishment of the calibration curve and lowering the costs. Linear calibration curve was found in the range of 1.7×10^-8M to at least 9.3×10^-7M Pb²⁺ after 3min of preconcentration. Statistic analysis of the results strongly suggests the MCGE exhibited a good analytical response, while the detection limits obtained for Pb（II） was 0.71×10^-8 M （calculated from 3S/N）. The modified electrodes displayed good resolution of the oxidation peaks. This work presented a new way to create a selective lead ion capturing film via modified cyclodextrin in design of specific lead sensors with high sensitivity. It has been a matter of deepening interest to quantify heavy metals in natural media such as air, soil and water, as much as in foodstuffs and biological fluids. Therefore, there has been a noticeable drive to develop diverse analytical techniques capable of detecting trace levels of the said metals in various matrices. The modified electrode to create high sensitivity highly selective mercury-free measurement sensors lead to a new approach. This electrode applied to the actual blood sample testing, the results of ICP-AES method and the results.In chapter five, the heterocyclic compounds modified electrode for detection of lead has been discussed. In this chapter, the discussions are about Morin, thiophene, pyrrole and their polymerization on the electrode surface. The article is divided into two sections. The heterocyclic compounds polymerization modified electrodes have been created. They both have a lead ion electrochemical response signal with free-mercury condition, and show a linear relationship with concentration of Pb （II）. Speculate as heterocyclic polymers of the nitrogen, sulfur, oxygen atoms exist, there is a certain sequestration with Pb （II）. But the role of specific mechanism still should be discussed.In chapter six, we summarized and gave objective comments on the results obtained. Meanwhile, the problems and shortcomings of this thesis were pointed out. Finally, we proposed the objects and schemes of further research.更多还原