螯合剂铁螯合值测定方法简介及评价

Introduction and assessment on measurement methods of Fe(Ⅲ) chelation value of chelating agent

介绍了目前常用螯合剂铁螯合值测定方法[络合滴定法、Fe(OH)3沉淀法、碘量法]及原理;采用这3种方法测定乙二胺四乙酸二钠(EDTA-2Na)铁螯合值,并对测定结果与理论值进行比较.结果表明:络合滴定法精密度及准确度均最高,操作简便,不受放置时间、溶液颜色的影响,且测定结果与理论值相符.Fe(OH)3沉淀法和碘量法误差大、准确度低,测定结果随样品质量变化而变化.因此,络合滴定法是测定螯合剂铁螯合值的最适宜方法.

The methods（complexometric titration method,ferric hydroxide precipitation method and iodo-metric method） commonly used to determine Fe（Ⅲ） chelation value and the measurement mechasim were intro-duced.The three methods were used to test Fe（Ⅲ） chelation values of disodium edta（EDTA-2Na）,and the mea-sured values were compared with theoretical values.The results showed that complexometric titration method had the highest precision and accuracy.And this method was simple,convenient and was not influenced by the placing time and sample color,and the measured value was in accord with the theoretical value.Both ferric hy-droxide precipitation method and iodometric method had big system error and low accuracy.And their measured values varied with the sample weight.Therefore,complexometric titration method was the most feasible method to determine Fe（Ⅲ）chelation value of chelating agents.