Cuprite-modified electrode for the detection of iodide species
Résumé
A cuprite-modified carbon paste electrode was evaluated as an electrochemical sensor for iodide species in aqueous medium. The overall analysis involved a two-step procedure: an open-circuit accumulation step followed by voltammetric quantification. In the preconcentration step, iodide was accumulated on cuprite (Cu2O) according to a surface precipitation mechanism leading to the formation of CuI. This solid was then detected either in the cathodic or in the anodic mode, the first process allowing multiple successive analyses without requiring any regeneration of the electrode surface, while the anodic scan resulted in the surface oxidation of Cu2O requiring the renewal of the electrode surface before any further accumulation experiment. The influence of various experimental parameters on the sensor response was investigated (i.e., pH, preconcentration time, detection mode, iodide concentration, Cu2O content into the paste). Reproducible results were obtained after optimization: a linear calibration was obtained in the 1×10−6 M to 2×10−5 M concentration range, with a detection limit of 5×10−7 M. The effect of chloride interference was also discussed.