Electrochemiluminescence behavior of meso-tetra(4-sulfonatophenyl)porphyrin in aqueous medium: its application for highly selective sensing of nanomolar Cu2+

The cathodic electrochemiluminescence (ECL) behavior of meso-tetra(4-sulfonatophenyl)porphyrin (TSPP) with potassium peroxydisulfate (K2S2O8) as the coreactant in aqueous solution with strong and stable emission was exploited to determine Cu2+ down to nanomolar concentration. Two possible reaction mechanisms have been proposed to understand the generation of ECL by the TSPP/K2S2O8 system. The effects of the concentration of TSPP and K2S2O8, pH of the medium, and scan rate on the ECL intensity were studied in detail. The ECL intensity was efficiently quenched by trace amounts of Cu2+. This phenomenon was used to develop a new method, which can offer rapid, reliable, and selective detection of Cu2+. Under the optimum conditions, plots of the ECL of the TSPP/K2S2O8 system versus the concentration of Cu2+ are linear in the range of 5 to 160 nM with a detection limit of 1.56 nM (S/N = 3). The proposed ECL sensor was successfully applied for analysis of tap and river water samples. It is anticipated that TSPP could be a new class of promising luminescent agent for ECL sensors.