Mechanism study on inorganic oxidants induced inhibition of Ru(bpy) _3~(2+) electrochemiluminescence and its application for sensitive determination of some inorganic oxidants

摘要

Inhibited Ru(bpy)_3~(2+) electrochemiluminescence by inorganic oxidants is investigated. Results showed that a number of inorganic oxidants can quench the ECL of Ru(bpy)_3~(2+)/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 MnO_4-, Cr_2O_7~(2-) and Fe(CN)_6~(3-) are linear in the range of 1 × 10 ~(-7) to 3 × 10~(-4) M for MnO_4- and Cr_2O_7~(2-), and 1 × 10~(-7) to 1 × 10~(-4) M for Fe(CN)_6~(3-), 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) _3~ (2+)/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)_3~(2+)/TPrA system. A mechanism based on consumption of TPrA intermediate (TPrA·) by inorganic oxidants was proposed.