CHROMATOGRAPHIC BEHAVIOR OF TRACE-METAL IONS ON A STRONG BASE ANION-EXCHANGE RESIN FUNCTIONALIZED BY AZO LIGANDS

A model which allows the evaluation of the elution volume V-E and the central point V-C of the breakthrough curve of a metal ion at trace le vel on a chromatographic column containing a chelating resin is presen ted. V-E and V-C mainly depend on the complexation properties of the a ctive groups, and on the acidity and composition of the aqueous soluti on, according to the Gibbs-Donnan model for the resin. The model has b een tested in the case of strong base anion exchange resins in chlorid e form functionalized with two different sulphonated azo ligands (T-az o-C, T-azo-R). The chromatographic behaviour of copper(II) and thorium (IV) is as expected from the formation of a complex with the azo dye i n the resin, while that of zinc(II) and cadmium(II) is fully described by also taking into account the formation of anionic chloro complexes inside the resin.