碱性消解-伏安极谱法测定土壤中六价铬

Determination of Hexavalent Chromium in Soil by Combination of Alkaline Digestion and Voltammetric Polarography

分析了汞滴尺寸、支持电介质等因素对碱性消解-伏安极谱法测定土壤中六价铬的影响。在优化实验条件下,该方法检出限为7.65μg/L,相对标准偏差（n=7）为4.6%。以2个样品为例,每个浓度进行6次平行测定,加入六价铬浓度为10μg/L,六价铬的回收率为91.4%~120%,RSD≤5%。与二苯碳酰二肼分光光度法进行比较,2种方法测定值基本一致。

A method has been established for the determination of hexavalent chromium in soil by alkaline digestion with voltammet- ric polarography. Factors that can influence the measurement, including working conditions of the instrument, sizes of the mercury drop, and concentrations of the electrolyte solution have been investigated in detail. Under the optimal condition, the method detect- tion limit is 7.65 μg/L, and the relative standard deviation （RSD） is 4.6% for seven consecutive measurements. Six parallel measurements were carried out for two samples having different concentrations of hexavalent chromium, each of which was spiked with 10 μg/L of hexavalent chromium standard. The recoveries of the hexavalent chromium were in the range of 91.4% - 120% and the RSDs were no more than 5%. The results obtained from this method and the spectrophotometric method were basically consist- ent.