紫外分光光度法测定水质六价铬的方法研究

Study on Determination of Hexavalent Chromium in Water by Ultraviolet Spectrophotometry

对紫外分光光度计法测定水质六价铬的国家地质方法进行了探讨,主要消除了样品中的悬浮物,在原方法的基础上加入试剂进行样品处理。虽然干过滤可以测定水质六价铬,而且过滤流程较为简单,但由于铬元素在水质中主要以三价和六价的形态存在,且存在于水中溶解态和颗粒态,致使过滤后测出的结果偏低。采用紫外分光光度法改进测定水质六价铬,分析了不同水质成分国家标准溶液样品,结果显示方法的重复性合格率达到98%,同时回收率也在95%~104%。分析结果的准确度、精密度和回收率均满足要求,该方法检出限为0.004 mg·L^(-1),精密度(RSD%,n=12)小于6%。对干过滤和不过滤及添加试剂前后测试结果进行对比,测定结果表明不过滤添加试剂时,相对误差均小于6%,与推荐值相符。

The national geological method for the determination of hexavalent chromium in water by ultraviolet spectrophotometer was discussed,the suspension in the sample was eliminated,and the reagent was added for the sample processing on the basis of the original method.Although dried filtration can measure the hexavalent chromium in the water,and the filtering process is relatively simple,the chromium is mainly in the form of three-valent and six-valent in the water,and it exists in the dissolved state and granular in the water,so that the measured result after filtering is low.In this article,the hexavalent chromium was determined by improved UV lighting method.The samples of national standard solutions with different water quality components were analyzed,and the results showed that the repeatability qualified rate of the method reached 98%,and the recovery rate was also between 95%and 104%.The accuracy,precision and recovery rate of the analysis results met the requirements.The detection limit of this method was 0.004 mg·L^(-1) and the RSD(n=12)was less than 6%.The test results with dry filtration and without filtration and before and after adding reagent were compared.The results showed that the relative error was less than 6%when adding reagent without filtration,which was consistent with the recommended value.