Electrochemiluminescence of the Ru(bpy)32+/S2O82- System in Purely Aqueous Solution at Carbon Paste Electrode

The electrochemiluminescence (ECL) of the Ru(bpy)32+/S2O82– system in purely aqueous solution at a carbon paste electrode can be clearly seen with the naked eye for Ru(bpy)32+ concentrations higher than 1 mmol L–1. The log–log plot of the emmitted light intensity vs. Ru(bpy)32+ concentration is linear over the region 10–3–10–7 mol L–1 with a correlation coefficient of 0.997. The ECL intensity increases linearly with the S2O82– concentration from 10–6 mol L–1 up to 0.3 mmol L–1 and drops off sharply at concentrations higher than 1 mmol L–1. In addition, a weak ECL signal was obtained when the potential was biased more negative than –0.6 V even in the absence of S2O82–.