Electrochemical impedance study and sensitive voltammetric determination of Pb(ii) at electrochemically activated glassy carbon electrodes

Abstract

An electrochemically oxidized glassy carbon electrode was found to work excellently in the trace determination of Pb(II) using square-wave anodic stripping voltammetry. The associated phenomena were unravelled using chronocoulometry, linear scan voltammetry and electrochemical impedance spectroscopy. The chronocoulometry results showed that the double layer charge enormously increased on preanodization due to the creation of phenolic and quinolic oxide functional groups on the surface. The ac impedance analysis indicated that the duplex-layer model could illustrate the oxidized glassy carbon electrode behaviour quantitatively. The experimental factors, including preanodization condition, square-wave parameter, supporting electrolyte and pH, were optimized. Using the optimum parameters, the calibration curve was constructed and the detection limit was found to be 0.7 ppb (S/N = 3). The electrode is quite stable for repetitive measurements. The practical application was demonstrated to estimate trace Pb(II) in groundwater with very good precision.