Electrocatalysis and amperometric detection at a ruthenium-modified indium-hexacyanoferrate film electrode

The electrocatalytic activity of a glassy carbon electrode modified with el ectrochemically deposited indium(III)-hexacyanoferrate (InHCF) film, which has been subsequently cycled in a solution of ruthenium(III), is described. Although the resulting ruthenium-modified InHCF thin film electrode behave s in a manner analogous to the parent InHCF film, its stability was found t o be greatly improved. Such a modified electrode was characterized, in acid ic (pH 2) 0.5 M KCl solutions, by cyclic voltammetry and flow injection ana lysis. It exhibits a high catalytic activity for the electrooxidation of so me some inorganic and organic compounds of analytical interest, such as As( III), S2O32-, cysteine, and 2-furaldehyde. The analytical applicability of this novel ruthenium-modified InHCF film electrode for the amperometric det ection in flowing streams is discussed. Repetitive sample injections with a mperometric detection of thiosulfate at +0.8 V (vs. Ag/AgCl) as applied pot ential produced a stable response over 8 h of operation, making it very att ractive for practical applications.