Behaviour of a chalcocite copper ion-selective electrode in solutions of iron(III) ions

The effect of iron(III) ions on the potential of the chalcocite electrode was investigated. Linear graphs were obtained for pFe(III) = 2-4, and were suitable for analytical purposes. The effect of ligands complexing iron(III) was studied, and the potential shown to be due to the concentration of free iron(III) ions only. The pH effect is mainly connected with solution reactions. A mechanism of potential response, based on a redox reaction, has been postulated, but the response does not depend on the redox potential in the bulk of the solution.