连续流动分析测定水质中耗氧量的方法研究

Determination of COD( Mn) in drinking water by continuous flow analysis

目的建立生活饮用水中耗氧量的连续流动分析方法,并与传统酸性高锰酸钾滴定法比较,以测定其适用性。方法水样和酸化的高锰酸钾溶液混合后,93℃在线加热,未反应的高锰酸钾溶液在520 nm波长下比色测定,AACE6.04分析软件采用反化学法测定出样品的峰高,根据峰高和校准曲线计算出样品的最终浓度。结果水样品的耗氧量浓度在0.10 mg/L^5 mg/L范围内,峰高与样品浓度线性相关良好(r=0.9996),检出限为0.013 mg/L,不同种类水样中0.5 mg/L、2.0 mg/L和3.5 mg/L的加标回收率为86.3%~107.3%;平行样的相对标准偏差≤4.75%(n=7);对27份水样进行测定,连续流动分析方法与人工滴定法的测定结果无显著性差异(P>0.05)。结论连续流动分析技术操作简单、快速,自动化程度高,测定水中耗氧量时准确度和重复性较好,适合于水质中耗氧量的常规测定分析。

Objective To establish a method for determination of chemical oxygen demand （COD（Mn）） in drinking water by continuous flow analysis（ CFA）, and compare its results with those of traditional acidic potassium permanganate titration to de- termine the applicability. Methods The water sample reacted with acidified potassium permanganate at 93℃ on - line. Unre- acted permanganate was involved for colorimetric determination at 520 nm. The sample concentration was calculated according to peak height and calibration curve which was analyzed by AACE6.0d analysis software with inverse analysis. Results The cor- relation coefficient of the peak height and concentration of COD（Mn） was 0. 9996 in the range of 0.05 mg/L ~ 5.0 mg/L and the detection limit was 0.013 mg/L. The recoveries of the method in different kinds of water samples were 86.3% - 107.3% with the RSDs less than 4.75% （n = 7 ）. There was no significant difference between continuous flow analysis and national titra- tion method by applying 27 water samples（P 〉 0.05）. Conclusion The method is simple, rapid and automatic with high accu- racy and good reproducibility, and it is suitable for routine analysis of chemical oxygen demand in drinking water.