Highly sensitive and selective amperometric sensors for nanomolar detection of iodate and periodate based on glassy carbon electrode modified with iridium oxide nanoparticles

Iridium oxide nanoparticles are grown on a glassy carbon electrode by electrode positing method. The electrochemical behavior and electrocatalytic activity of modified electrode towards reduction of iodate and periodate are studied. The reductions of both ions occur at the unusual positive peak potential of 0.7 V vs. reference electrode. The modified electrode is employed successfully for iodate and periodates detection using cyclic voltammetry, hydrodynamic amperometry and flow injection analysis (FIA). In the performed experiments, flow injection amperometric determination of iodate and periodate yielded calibration curves with the following characteristics: linear dynamic range up to 100 and 80 mu M, sensitivity of 140.9 and 150.6 nA mu M-1 and detection limits of 5 and 36nM, respectively. The repeatability of the modified electrode for 21 injections of 1.5 mu M of iodate solution is 1.5%. The interference effects of NO2-, NO3-, ClO3-, BrO3-. ClO4-. SO42-. Cu2+, Zn2+, Mn2+, Mg2+, Cd2+, Ca2+, Na+, K+, NH4+ and K+, CH3COO- and glucose were negligible at the concentration ratio of more than 1000. The obtained attractive analytical performance together with high selectivity and simplicity of the proposed method provide an effective and a novel modified electrode to develop an iodate and periodate sensor. Sensitivity, selectivity, the liner concentration range and the detection limit of the developed sensor are all much better than all known similar sensors in the literature for iodate and periodate determination. (C) 2009 Elsevier B.V. All rights reserved.