Determination of p-aminobenzenesulfonic acid based on the electrochemiluminescence quenching of tris (2,2'-bipyridine)-ruthenium (II)

Abstract

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 (KSV) 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.