摘要
建立快速测定水中化学需氧量(COD)的重铬酸钾光度法。样品消解温度为165℃,消解时间为15 min。当水中含有氯离子时,可加入硫酸汞掩蔽剂消除氯离子影响,其加入量按每毫克氯离子加入20 mg硫酸汞计算。该方法检测范围为20~800 mg/L,当水中COD质量浓度大于800 mg/L时应先进行稀释,然后测定;当COD质量浓度小于20 mg/L时,可以采用真空蒸馏法浓缩,以提高COD质量浓度。采用该方法对COD质量浓度为300 mg/L的标准溶液进行测定,测定结果的相对标准偏差为0.7%(n=6),相对误差为-2.0%。分别采用所建方法和国家标准方法HJ 828—2017(重铬酸钾回流消解滴定法)测定两个不同水样,相对偏差分别为-1.6%和-1.1%。该方法适用于水中COD的快速测定。
A method of the rapid determination of chemical oxygen demand(COD)in water by potassium dichromate spectrophotometry was established.The samples were digested at 165℃for 15 min.When the water contains chloride ions,the mercury sulfate masking agent could be added to eliminate the influence of chloride ions,and the addition amount was calculated by adding 20 mg of mercury sulfate per mg of chloride ion.The detection range of the method was 20-800 mg/L.When the mass concentration of COD in water was more than 800 mg/L,the sample should be diluted before being measured.When the mass concentration of COD was less than 20 mg/L,the sample should be concentrated by vacuum distillation to improve the mass concentration of COD.The standard solution with the mass concentration of COD of 300 mg/L was determined by the method,the relative standard deviation of the determination results was 0.7%(n=6),and the relative error was-2.0%.The established method and the national standard method HJ 828-2017(potassium dichromate reflux digestion titration)were used to determine two different water samples,the relative deviations were-1.6%and-1.1%,respectively.The method is suitable for the rapid determination of COD in water.
作者
林国辉
Lin Guohui(Fujian Metrology Institute,Fuzhou 350003,China)
出处
《化学分析计量》
CAS
2021年第10期37-41,共5页
Chemical Analysis And Meterage
关键词
重铬酸钾
分光光度法
化学需氧量
potassium dichromate
spectrophotometry
chemical oxygen demand(COD)
