Mechanism study on inorganic oxidants induced inhibition of Ru(bpy)32+ electrochemiluminescence and its application for sensitive determination of some inorganic oxidants

Inhibited Ru(bpy)32+ electrochemiluminescence by inorganic oxidants is investigated. Results showed that a number of inorganic oxidants can quench the ECL of Ru(bpy)32+/tri-n-propylamine (TPrA) system, and the logarithm of the decrease in ECL intensity (ΔI) was proportional to the logarithm of analyte concentrations. Based on which, a sensitive approach for detection of these inorganic oxidants was established, e.g. the log-log plots of ΔI versus the concentration of MnO4−, Cr2O72− and Fe(CN)63− are linear in the range of 1 × 10−7 to 3 × 10−4 M for MnO4− and Cr2O72−, and 1 × 10−7 to 1 × 10−4 M for Fe(CN)63−, with the limit of detection (LOD) of 8.0 × 10−8 M, 2 × 10−8 M, and 1 × 10−8 M, respectively. A series of experiments such as a comparison of the inhibitory effect of different compounds on Ru(bpy)32+/TPrA ECL, ECL emission spectra, UV-Vis absorption spectra etc. were investigated in order to discover how these inorganic analytes quench the ECL of Ru(bpy)32+/TPrA system. A mechanism based on consumption of TPrA intermediate (TPrA·) by inorganic oxidants was proposed.