Anodic stripping determination of Pt(IV) based on the anodic oxidation of In from electrochemically deposited Pt–In alloy phases

A simple, rapid, and sensitive anodic stripping voltammetric method for the determination of Pt (IV) is described. It is based on depositing an intermetallic indium–platinum alloy phase on the surface of a modified graphite electrode, and recording the oxidation peak of indium from that alloy phase with the help of linear scan voltammetry. A systematic study of the behavior of different In–Pt phases revealed that the peak potential of indium oxidation from the different phases can be explained on the basis of simple thermodynamic considerations. Different alloy phases have characteristic peak potentials. For the purpose of analysis, it is possible to choose such conditions that only one specific alloy phase forms, viz. PtIn. This is the case for a concentration (milligrams per liter) ratio of In(III)/Pt(IV)?=?50,000:1, at least.