Electrochemiluminescence response of novel ruthenium (II) complex/Nafion film-coated electrodes and its stability

Two novel ruthenium (II) complexes (Ru-II) having four positive charges were prepared so as to be strongly incorporated into a Nafion film. Complex A is a bis-Ru-II complex bound with a long alkyl chain and Complex B is a Ru-II having two pyridinium pendants. A flow-through detector using Ru-II/Nafion-coated Au electrdodes was applied for the determination of amino acids. The Complex A electrode more strongly responded to proline than did the Ru(bpy)(3)(2+) electrode, and showed a more stable response than did the Ru(bpy)(3)(2+) electrode. On the other hand, the Complex B electrode showed almost the same response profile for amino acids as did the Ru(bpy)(3)(2+) electrode. The response intensity was 1/60-times less strong than that of the Complex A electrode, perhaps due to the consumption of a strong reducing agent which may have been generated from oxidation of amino acids.