Electrochemiluminescence of dichlorotris (1,10-phenanthroline) ruthenium (II) with peroxydisulfate in purely aqueous solution at carbon paste electrode

Abstract

The electrochemiluminescence (ECL) of dichlorotris (1,10-phenanthroline) ruthenium (II) [Ru phen 3 2+ ] with peroxydisulfate (S 2O 8 2−) was first described. The use of carbon paste electrodes, organic solvent modified electrodes, allowed obtaining ECL in purely aqueous solution. The ECL produced by the reaction of electrogenerated Ru phen 3 + with the strongly oxidizing intermediate SO 4 −·, was observed only when the applied potential was negative enough to reduce Ru phen 3 2+ . In comparison with Ru bpy 3 2+ /S 2O 8 2− ECL, the Ru(phen) 3 2+/O 8 2−/S 2O 8 2− ECL was more stable in aqueous solution. It was not affected by the storage of the carbon paste electrodes, and it quenched only at quite high S 2O 8 2− concentrations. The ECL intensity was a function of S 2O 8 2− concentration, increasing linearly with the S 2O 8 2− concentration from 5×10 −6 to 2×10 −3 mol l −1, and dropping off sharply at S 2O 8 2− concentration higher than 20 mmol l −1. The proposed ECL method with Ru phen 3 2+ was sensitive and selective for the determination of S 2O 8 2−.