高浓度游离氯检测时显色后褪色的原因分析及改进方法研究  

Analysis on the cause of fade after color development during monitoring of high concentration free chlorine and its improvement methods

作　　者：代佼 杨玖 王珍珍 夏勇 DAI Jiao;YANG Jiu;WANG Zhen-zhen;XIA Yong(East Ecological Environment Monitoring Station of Panzhihua,Panzhihua 617000,China;School of Information Science and Engineering,Fudan University,Shanghai 200433,China;Sichuan Panzhihuhua Ecological Environment Monitoring Center Station,Panzhihua 617000,China)

机构地区：[1]攀枝花市东区生态环境监测站,四川攀枝花617000 [2]复旦大学信息科学与工程学院,上海200433 [3]四川省攀枝花生态环境监测中心站,四川攀枝花617000

出　　处：《化学研究与应用》2024年第8期1896-1901,共6页Chemical Research and Application

基　　金：2023年度攀枝花市市级指导性科技计划项目(2023ZD-S-61)资助。

摘　　要：采用N,N-二乙基-1,4-苯二胺(N,N-Diethyl-1,4-phenylenediamine,DPD)分光光度法测定游离氯浓度较高的水样时,检测过程经常出现显色后褪色的异常现象,导致检测结果严重偏低。本文通过分析游离氯浓度与吸光度的对应变化关系,来探讨显色与褪色的反应机理,并以此为依据来提出改进方法。实验发现,随着游离氯浓度增加,吸光度呈现先增后减的变化趋势。结合相关文献分析,这是由于过量游离氯与红色显色产物N,N-二乙基对醌二亚胺发生氧化反应,导致红色消褪。在此提出采用游离氯快速检测试纸预检的方法,根据预判游离氯浓度范围来选择合适稀释倍数进行显色分析,本文提供了最优稀释倍数选取方案。结果表明,采用改进后的方法对15份实际样品进行测定,与原方法相比,改进后的方法检测结果准确率提升40%,总耗时缩短50%~81%,只需稀释操作1次,可有效解决显色后褪色的问题。An abnormal phenomenon of fade after color development used to occur during the experiment,when N,N-diethyl-1,4-phenylenediamine(DPD) spectrophotometry was used to determine water samples with high free chlorine concentration.As a result,the test results were seriouly lower than the true value.The reaction mechanism of color fading was discussed in this paper,based on the relationship analysis of free chlorine concentrations and their corresponding absorbances.Then the improvement methods was proposed.It was found that the absorbance increased first and then decreased with the increase of free chloride concentration.Combined with the analysis of the relevant literatures,it was found that the red fade was due to the oxidation reaction between the excess free chlorine and the red chromogenic product N,N-diethyl on quinine diimine.Herein,a pre-detection method of free chlorine by the rapid test strip was proposed and a selection scheme of optimal dilution multiple was provided.The appropriate dilution could be selected according to the predicted concentration range of free chlorine.The improved method was applied to 15 actual samples.The results showed that the accuracy was increased by 40%,the total time was shortened by 50%~81%,compared with the original method.Only one dilution operation was needed,and could effectively solve the problem of color fade.The improved method is convenient,rapid and accurate.It could effectively avoid the problem that the high concentration of free chlorine were detected as a lower concentrationlower than the true value.This method might be used as a technical supplement to the standard analysis method.

关 键 词：游离氯检测 N N-二乙基-1 4-苯二胺分光光度法 褪色 改进方法 

分 类 号：O657.3[理学—分析化学]