在高铁背景下二价铁含量的测定方法浅析

常规实验方法中,常量二价铁的浓度一般使用氧化还原滴定的方法测定,误差可以控制在0.2%以内;微量二价铁的浓度测定一般采用分光光度法,误差允许在5%以内。但是当待测样本中有三价铁时,由于三价铁的干扰,导致滴定法的终点不易准确观察到,而分光光度法的吸光度值受到三价铁显色的影响也很难把握,也影响着二价铁的测定。本文将通过选择不同的滴定手段和分光光度法,准确获得二价铁可以测得的最低浓度和三价铁与二价铁的最大比值。

In the routine experimental method,the concentration of constant Fe2＋ is usually measured by redox titration,its accidental error is less than 0.2%;The concentration of trace Fe2＋ is generally measured by spectrophotometry, which has a less than 5% accidental error.However, if Fe3＋ is present in the sample, the end point of the redox titration will be difficult to observe because of the interfere of the Fe3＋;And the absorbance value of spectrophotometry method is also affected by the color of the Fe3＋,which will cause immeasurable error. In this paper, we will chooose different titration and spectrophotometry methods to obtain the minimum concentration of the Fe2＋ and the maximum ratio of Fe3＋ and Fe2＋ in which the concentration of Fe2＋could be measured accurately.