邻菲罗啉分光光度法测定含EDTA溶液中Fe^3＋的改进

Improvement on Determination of Fe^(3+) with the Solution Containing EDTA by Phenanthroline Spectrophotometry

为提高邻菲罗啉分光光度法测定含EDTA溶液中的Fe^(3+)离子准确性,通过提前加入显色剂以及水浴加热代替电炉加热等改进方法。结果表明,含有EDTA溶液中铁离子回收率基本为100%,该改进方法操作简便且具有很好的准确度和重现性。EDTA/Fe摩尔比对测定影响很大,当两者比例<1.5时,改进方法可以准确的测出铁离子含量,铁离子回收率基本在99%以上;两者比例>2时,铁离子回收率低于95%,且呈下降趋势。因此对于高摩尔比的溶液应延长显色时间或考虑采用掩蔽剂,减少过量EDTA的干扰。

The error of determination of Fe3＋ in the solution containing EDTA by Phenanthroline spectrophotometry was large. Adding chromogenic agent in advance and substituting heating furnace with water bath heating could improve the accuracy of the determination of Fe3＋ in the solution containing EDTA. The results showed that the recovery rate of iron ions was basically equal to 100%. The improved method is easy to operate and has a good accuracy and reproducibility. The EDTA/Fe mole ratio has great influence on the determination. When the ratio is below 1.5, the improved method can accurately measured the iron ion content with recovery rate of iron ion being basically larger than 99%. When the ratio is higher than 2, the recovery rate of iron ion is less than 95% and accompaned downward trend. So for the high molar ratio of EDTA/Fe coloration time should be prolonged or masking agent is used to reduce excessive interference of EDTA.