烘箱消解-重铬酸钾滴定法测定水质中化学需氧量

Determination of chemical oxygen demand in water by oven digestion–potassium dichromate titration

建立烘箱消解–重铬酸钾滴定法测定水质中化学需氧量(COD)的分析方法。在HJ 828–2017重铬酸钾法测定水质中COD的基础上,用烘箱消解法替代回流煮沸消解法,通过正交试验确定消解条件,消解温度为165℃,消解时间为25 min。在优化的试验条件下,对水样和标准样品进行测定,水样测定结果的相对标准偏差为0.2%~1.9%(n=5),标准样品的相对偏差为–0.4%~1.6%,平均加标回收率为99.5%。该方法操作简便,消解时间短,准确度高,可用于大批量样品的快速测定。

A method for the determination of chemical oxygen demand(COD)in water by oven digestion–potassium dichromate titration was established.Based on the HJ 828–2017 potassium dichromate method for the determination of COD in water,oven digestion method was used instead of reflux boiling digestion method.The digestion conditions were determined by orthogonal experiments.The digestion temperature was 165℃ and the digestion time was 25 min.Under optimized test conditions,the water samples and standard samples were measured.The relative standard deviation of the water samples was 0.2%–1.9%(n=5),the relative error of the standard samples was-0.4%-1.6%,and the average recovery rate was 99.5%.The method is simple to operate,short digestion time,high accuracy,and it can be used for rapid determination of large quantities of samples.