Hulanicki A, Karwowska R
Institute of Chemistry, University, Warsaw, Poland.
Talanta. 1971 Mar;18(3):239-45. doi: 10.1016/0039-9140(71)80037-1.
Potentiometric titrations of metal ions with EDTA have been carried out with a platinum or graphite electrode and the Fe(III)/Fe(II) redox system. In the absence of oxygen and for pH < 2 the titration curves may be described by an equation similar to that given previously for titrations with silver and mercury electrodes. Titration curves for bismuth and indium, which are more strongly complexed than iron, are asymmetrical and useful for analytical purposes. When the titrated ions are complexed less strongly than iron(III) ions the kinetics of metal complexation have a pronounced effect. The titration curves of thorium and copper, which react more rapidly than iron, are analytically useful. The curves recorded rapidly after titrant additions have a better end-point break than those which correspond to thermodynamic equilibrium. When a metal, e.g., nickel, is weakly bound by EDTA, and reacts more slowly than iron, a very small end-point break or none at all is observed.
使用铂电极或石墨电极以及Fe(III)/Fe(II)氧化还原体系，对金属离子与乙二胺四乙酸（EDTA）进行了电位滴定。在无氧且pH < 2的情况下，滴定曲线可用一个类似于先前给出的、用于银电极和汞电极滴定的方程来描述。铋和铟比铁更易形成络合物，它们的滴定曲线不对称，可用于分析目的。当被滴定离子形成络合物的强度比铁(III)离子弱时，金属络合动力学有显著影响。钍和铜的反应比铁快，它们的滴定曲线在分析上是有用的。滴定剂加入后快速记录的曲线比对应于热力学平衡的曲线有更好的终点突跃。当一种金属，例如镍，与EDTA结合较弱且反应比铁慢时，观察到的终点突跃非常小或根本没有。
