密封消解法测定COD的方法研究

Study on method of sealed digestion for COD determination

以硫酸锰代替硫酸银作催化剂,对密封消解法测定COD的条件进行了优化,得出最佳消解条件:消解温度为160℃,消解时间为35 min,催化剂质量浓度10 g/L。进行了高、中、低3个不同浓度的加标回收率试验,相应的回收率分别为98.72%,101.2%,97.24%,平均值为99.05%,RSD为1.08%。测定了实际水样的COD值,并与标准法进行了对比,统计检验表明,两方法间无显著性差异,但密封消解法具有简便快速、分析费用低、适于批量样品测定的优点。

Using manganese sulfate instead of silver sulfate as catalyst, a sealed digestion method was developed for determination of chemical oxygen demand （COD）. The parameters of COD determination by the sealed digestion method were optimized, and the results are as follows： digestion temperature 160℃ ,digestion time 35 min,the catalyst concentration 10 g/L. The recoveries of standard material at high, medium, low concentration are 98.72%, 101.2 %, 97.24 % respectively, the average recovery is 99.05 % and RSD is 1.08 %. The sealed digestion method was compared with the standard method through analyzing five water samples,and good agreement results were obtained. Statistical analysis indicates that there is no significant difference in the results between the two methods, but the sealed digestion method was simple, rapid, low-cost, and suitable for determination of bulk samples.