Mechanism for inhibition of Ru(bpy)32+/DBAE electrochemiluminescence system by dopamine

Recently, 2-(dibutylamino)ethanol (DBAE) was reported to be a more efficient co-reactant than the widely used tripropylamine (TPrA) for electrochemiluminescence (ECL) of Ru(bpy)32+. Therefore, the new Ru(bpy)32+/DBAE ECL system seemed to be great potential for its application in analytical chemistry. Dopamine (DA) was found to be able to inhibit the ECL of Ru(bpy)32+/DBAE system. Under the optimum conditions, the logarithmic plot of the inhibited ECL versus the concentration of DA was linear in the range of 5 × 10−10–7 × 10−7 M with the detection limit of 4.0 × 10−11 M. A mechanism based on the quenching of reductive-form DBAE by DA-oxidation products was proposed, which was quite different from the mechanism for Ru(bpy)32+/TPrA/DA system reported previously.