Determination of Complexable Metals by Chelometric Titration.

摘要

A rapid,simple method for the determination of total complexable metal ions (Fe3exp + ,Al exp 3+ ,Mn exp 2+ ,Ni exp 2+ ,Co exp 2+ ,Pb exp 2+ ,and Rare Earths) in feed to the Hanford strontium recovery process has been developed. The method consists of complexing the metal ions with EDTA and titrating the excess with copper (II) ion. Pyrocatechol violet is used as a colorimetric end point indicator. Samples of actual process feed were analyzed and the results compared very favorably with results by atomic absorption. Use of a synthetic feed standard showed an average accuracy of 99.7% and a relative precision of +- 1.9% (95% C.L.). Interference studies run on the method show that oxalate and phosphate interfere above mole ratios of 0.1and 0.3,respectively (anion :total complexable cations). Of the complexable metal ions commonly encountered in this feed (specifically excluding alkali and alkaline-earth metals),the only complexable ion not determinable by this method is Cr. (ERA citation 03:031435)