Co-reactant-on-Demand ECL: Electrogenerated Chemiluminescence by the in Situ Production of S2O82- at Boron-Doped Diamond Electrodes

A novel co-reactant-free electrogenerated chemiluminescence (ECL) system is developed where Ru(bpy)(3)(2+) emission is obtained on boron doped diamond (BDD) electrodes. The method exploits the unique ability of BDD to operate at very high oxidation potential in aqueous solutions and to promote the conversion of inert SO42- into the reactive co-reactant S2O82-. This novel procedure is rather straightforward, not requiring any particular electrode geometry, and since the co-reactant is only generated in situ, the interference with biological samples is minimized. The underlying mechanism is similar to that of the Ru(bpy)(3)(2+)/S2O82- system; however, the intensity of the emitted signal increases linearly with [SO42-] up to similar to 0.6 M, with possible implications for analytical uses of the proposed procedure.