Incorporation of hydroxamic acid ligands into Nafion film electrodes

This paper describes studies on Nafion-coated glassy carbon electrodes incorporating hydroxamic acids. Desferrioxamine, a trihydroxamic acid, and glycine hydroxamate, a monohydroxamic acid, can be incorporated by ion exchange into the Nafion film. These ligands were detected in the film visually, after reaction with iron(III), and electrochemically, by voltammetric oxidation. The complex of iron(III) with desferrioxamine was electrochemically active at the iron(III) centre in the Nafion film. The electrochemistry of this complex in the film agrees well with the solution electrochemistry reported by other workers: irreversible at low pH and reversible at high pH. The ability of the modified electrode to act as a sensor for iron(III) was assessed. Complexation of iron(III) from dilute solution into the polymer film was possible, and 5 × 10–7 mol l–1 iron(III) could be detected after a 10 min preconcentration, with differential-pulse voltammetric detection in pH 10 ammoniacal buffer.