消除化学需氧量测定时氯离子干扰的方法论述

Discussion on the Method of Eliminating the Interference of Chloride Ions in the Determination of Chemical Oxygen Demand

化学需氧量(COD_(cr))作为一项衡量水体中有机污染物相对含量的综合指标,是水质监测中的重要因子。重铬酸盐法是测定化学需氧量(COD_(cr))最常用的方法,但其测定结果易受水样中氯离子浓度影响,介绍了4种消除氯离子干扰的方法:硫酸汞屏蔽法、氯气校正法、银盐抑制法及标准曲线校正法,同时对比了各自适用范围和优缺点,以供监测人员开展监测工作时能因地制宜选择合适的干扰消除方法以提高分析测试结果的准确度。

As a comprehensive index to measure the relative content of organic pollutants in water,chemical oxy-gen demand(COD_(cr))is an important factor in water quality monitoring.The dichromate method is the most commonly-used method to determine COD_(cr),but its determination result is easily affected by the concentration of chloride ions in the water sample.This paper introduces four methods to eliminate chloride ion interference:the mercury sulfate shielding method,the chlorine correction method,the silver salt inhibition method and the standard curve correction method,and compares their respective application scopes and advantages and disadvantages,so as to help the monitoring personnel to choose the appropriate interference elimination method according to local con-ditions to improve the accuracy of analying test results.