重铬酸盐法和快速检测仪法测定水质化学需氧量(COD)对比研究

Comparative Study on Determination of Chemical Oxygen Demand in Water by Dichromate Method and Rapid Test Method

为了科学合理地选择快捷经济的水质化学需氧量(COD)测定方法,课题组选取两种目前常用的水质COD测定方法:重铬酸盐法和快速检测仪法,利用标准水样对比研究了它们的准确度、精密度、加标回收率和高浓度稀释倍数,还比较了两种方法的实验耗时、废液产生量、试验成本、试剂危害、试剂配制难易程度以及影响因素。结果表明:这两种方法测定的结果均达到了国家标准要求且都具有较高的准确度和精密度。总体上,前者的准确度弱于后者,但前者的精密度优于后者。重铬酸盐法适用范围较广,但分析步骤烦琐耗时多,危险系数高,对分析人员技术要求较高;而快速检测仪法操作简单、快速、安全,污染小,可批量检测样品。在具备实验条件的情况下,可优先采用快速检测仪法测定水质COD。

In order to scientifically and rationally select a fast and economic method for determining chemical oxygen demand(COD)of water quality,the paper selects two common methods to determine COD in water:dichromate method and rapid test method.Their accuracy,precision,recovery rate and high concentration dilution ratio are compared by using standard water samples,and the experimental time,amount of waste liquid,test cost,detriment of reagent,preparation difficulty of reagent and influencing factors of the two methods are compared as well.The results show that both methods are of good accuracy and precision when meeting the requirements of national standards.In general,the former is less accurate than that of the latter,but the precision of the former is better.The dichromate method has a wide application range,but with a high risk factor since the analytical steps are complicated and time-consuming therefore very demanding technical requirements for the analysts,while the rapid test method is simple,fast,safe,low-polluting and available for batch testing.Conditions permitted,the rapid test method should be preferentially used to determine COD.