密封消解法测定CODMn

Detection of COD_(Mn) by Seal Digestion

目的探索采用密封消解测定高锰酸盐指数的新方法,为监测和防治提供及时、可靠的数据.方法该法以《水和废水监测分析方法》中的标准法为基础,用密封消解法代替水浴加热,消解后仍然用滴定法测定,同时为了消除KMnO4自身分解对测定结果的影响,研究采用分光光度法建立吸光度和KMnO4浓度曲线测定自分解消耗量,并从滴定测定结果中扣除,保证了结果的准确性.结果标准曲线的相关系数r=0.999 8,消解时间15 min、温度150℃,测定结果的相对标准偏差小于2%,相对误差在5%~6%之间,精密度与准确度均能满足要求.结论在95%的置信度下,与标准法进行t值检验（t〈2.23）,说明两种方法不存在显著性差异.研究表明高锰酸盐指数测定的密封消解法具有省时节能、试剂用量少、操作简便、可批量处理等优点.

A new detection method for chemical oxidation demand（CODMn）is studied in order to provide instant and reliable data for environmental monitoring and protection. This method was based on the standard method given in the ＂Monitoring and Analysis Method for Water and Wastewater＂, with the water bath heating replaced by seal digestion. The titration was still used after digestion. The self-decomposition of KMnO4 was measured by a standard curve of KMnO4 concentrations against absorbance acquired by spectrometry in order to minimize the overestimation. The correlation rate（r） of the standard curve was 0.999 8, and the digestion duration was 15 min at the temperature of 150 ℃. The relative deviation of the results were less than 2 %, and the standard error was between 5 % and 6 %. At the confidence level of 95 %, this method was tested against the standard method by T hypothesis（t〈 2.23）with no significant difference. The method has showed its advantages in time-efficient, bath handling and easy manipulation.