Dithizone-anchored poly(vinylpyridine) as a chelating resin for the preconcentration and separation of gold(III) from platinum(IV), copper(II) and mercury(II)

Abstract

Dithizone, one of the specific reagents for the determination of gold, was coupled to cross-linked poly(vinylpyridine) and was used for the preconcentration of nanogram levels of gold. The polymeric support was characterized as regards the extent of dithizone coupling and its thermal properties. The support was also used under batch and column conditions for the preconcentration of gold. Various conditions such as pH, temperature, flow rate and column parameters were optimized for the maximum amount of gold loading. A gold loading of 240 mg per gram of support was achieved under the optimized conditions. Mixtures of 0.2 mol dm^–3 HCl and 2.0% thiourea (1 + 1) and of 5.0 mol dm^–3 HCl and 1.0 mol dm^–3 HNO₃(1 + 1) could elute gold quantitatively. Separation of gold from binary and ternary mixtures of platinum, copper and mercury was achieved without any cross-contamination.