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DEVELOPMENT OF MINIATURIZED ANALYTICAL SYSTEM FOR RESIDUAL CHLORINE WITH ELECTROCHEMICAL SENSORS

带电化学传感器的小型余氯分析系统的开发

基本信息

批准号：
15550067
负责人：
JIN Jiye
金额：
$ 1.98万
依托单位：
Shinshu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Chlorine in aqueous solutions is used for a number of purposes, such as disinfection and bleaching, and also as a powerful oxidizing agent in various manufacturing processes. It is known that chlorine is highly toxic, and additionally it can further react with other substances, such as phenols, in environment to produce chlorophenols, which are suspected to be carcinogens. Thus, the development of the new methods and devices for the reliable and continuous measurement of residual chlorine at trace levels had been conducted in the present work.Residual chlorine in water is generally present in the fibrin of hypochlorous acid (HOCl), or its conjugated base, the hypochlorite ion (ClO-). It was confirmed in this study that gold electrode exhibited very large reductive currents as well as good stability compared with platinum and glassy carbon electrodes in the pH range of 4-8. Based on the electrochemical sensors with gold electrode, the present study developed a portable miniaturized FIA … More system for on-site monitoring of residual chlorine in environmental samples. As for the purpose of on-site determination, miniaturization of the potentiostat along with a reduction in the complexity of the chip, low power consumption and a high dynamic range was developed in the current work. The potentiostat was built using an embedded controller microprocessor, an A/D converter a D/A converter, and operational amplifiers. It is available operated by a battery for a video camcorder (Sony NP-F550, 7.2 V 1500 mA/H). The size of the potentiostat is 150×100×40 mm and weight is only 350 g. The electrochemical measurements were controlled by a notebook computer and a laboratory-written software package via an RS-232C interface. It was confirmed that the amperometric response increased in proportion to the chlorine concentration up to 5μg/ml, and the detection limit for chlorine was 0.05 μg/ml. Besides a drastic reduction the size of the analytical system, such miniaturization achieved the advantages of increased speed, minimal mobile-phase consumption, and high sensitivity. The proposed method was successfully applied to the determination of residual chlorine in samples of pool water and tap water. The results were well agreed with those obtained by the N,N-diethyl-p-phenylenediamine (DPD) photometric method.The electrochemical behavior of trace chlorine was also studied in the presence of DPD at glassy carbon electrode by square wave voltammetry. In the lower pH value, a new reduction wave (+0.4 V vs Ag/AgCl) was observed, which is closely followed by the reduction of DPD (+0.5 V vs Ag/AgCl). The new peak at ca. +0.4 V was suggested to be generated by chlorinated product of DPD which is in proportion to the concentration of chlorine. But this peak was seriously overlapped by the background of DPD when the concentration of chlorine is low. In this study, signals-ratio method combined with wavelet transform was proposed for the resolution of a weak voltanunteric signal overlapped by other coexisted components. With the proposed method, the overlapped voltammetric peaks can be well separated and thereby the chlorine at trace level could be determined in a linear range of 0 to 100 μM with a detection limit of 0.5 μM. The advantages of proposed method are sensitive and free of some oxidant interthrences which could be a problem in DPD colorimetric method. The mechanism and the application in determination of real samples are now in progress. Less

水溶液中的氯用于许多目的，例如消毒和漂白，并且还在各种制造过程中作为强氧化剂。众所周知，氯具有很高的毒性，此外，它还可以与环境中的其他物质（如酚类）进一步反应，产生氯酚，氯酚被怀疑是致癌物质。因此，本研究开发了一种新的、可靠的、连续的痕量余氯测定方法和装置。水中的余氯一般以次氯酸（HOCl）或其共轭碱次氯酸根离子（ClO-）的形式存在。结果表明，金电极在pH 4 ~ 8范围内具有很大的还原电流和良好的稳定性。本研究以金电极电化学传感器为基础，研制了一种便携式微型流动注射分析仪 ...更多信息环境样品中余氯现场监测系统。至于现场测定的目的，小型化的恒电位仪沿着芯片的复杂性，低功耗和高动态范围的减少，在当前的工作中开发。恒电位仪由嵌入式微处理器、A/D转换器、D/A转换器和运算放大器组成。它是可用的视频摄像机（索尼NP-F550，7.2 V 1500 mA/H）的电池操作。恒电位仪的尺寸为150×100×40 mm，重量仅为350 g。电化学测量由笔记本电脑和实验室编写的软件包通过RS-232 C接口控制。结果表明，在5μg/ml以下，电流响应随氯浓度的增加而增加，检出限为0.05 μg/ml。除了大大减少了分析系统的大小，这种小型化实现了增加的速度，最小的流动相消耗，和高灵敏度的优点。该方法已成功地应用于游泳池水和自来水中余氯的测定。用方波伏安法研究了微量氯在DPD存在下在玻碳电极上的电化学行为。在较低的pH值下，观察到一个新的还原波（+0.4Vvs Ag/AgCl），紧随其后的是DPD的还原（+0.5Vvs Ag/AgCl）。新的高峰在CA。DPD的氯化产物产生+0.4V，与氯的浓度成正比。但当氯浓度较低时，该峰与DPD背景严重重叠。本文提出了一种结合小波变换的信号比法，用于分辨被其它共存分量叠加的微弱伏安信号。该方法能很好地分离重叠的伏安峰，从而可在0 ~ 100 μM范围内测定痕量氯，检出限为0.5 μM。该方法具有灵敏度高、不受氧化剂干扰等优点。其机理及在真实的样品测定中的应用正在研究中。少