Determination of p‐Aminobenzenesulfonic acid based on the electrochemiluminescence quenching of tris (2,2 ’ ‐bipyridine)‐ ruthenium (II)

This study describes the quenching effects of p‐aminobenzenesulfonic acid (p‐ABSA) based on electrochemiluminescence (ECL) of the tris (2,2 ’ ‐bipyridyl)‐ruthenium(II)(Ru(bpy) 3 2+ )/tri‐n‐propylamine (TPrA) system in aqueous solution. Quenching behaviours were observed with a 200‐fold excess of p‐ABSA over Ru(bpy) 3 2+ . In the presence of 0.1 M TPrA, the Stern‐Volmer constant (K SV ) of ECL quenching was as high as 1.39 × 10 4  M ‐1 for p‐ABSA. The logarithmic plot of inhibited ECL versus concentration of p‐ABSA was linear over the range of 6.0 × 10 ‐6 ‐3.0 × 10 ‐4  mol/L. The corresponding limit of detection was 1.2 × 10 ‐6  mol/L for p‐ABSA (S/N = 3). The mechanism of quenching is believed to involve an energy transfer from the excited‐state luminophore to a dimer of p‐ABSA and the adsorption of free radicals of p‐ABSA at the electrode surface that impeded the oxidation of the Ru(bpy) 3 2+ /TPrA system. Copyright © 2012 John Wiley & Sons, Ltd.