Electrochemical study of iodide in the presence of phenol and o-cresol: Application to the catalytic determination of phenol and o-cresol

The electrochemical oxidation of iodide in the presence of phenol and o-cresol was investigated at a glassy carbon electrode in buffered media by cyclic voltammetry, linear sweep voltammetry and controlled-potential coulometry. The experimental results indicate that the phenol and o-cresol convert to their derivatives after participating in a halogenation coupled reaction (quasi-catalytic reaction) following the oxidation of iodide to iodine. The concentrations of phenol and o-cresol have been determined in aqueous solutions according to the linear dependence of quasi-catalytic peak currents with the concentration. The calibration graphs show two linear sections of 0.0 to 1.0 x 10(-4) M and 2.0 x 10(-4) to 1.0 x 10(-3) M for phenol and 4.2 x 10(-5) to 1.0 x 10(-4) M and 2.0 x 10(-4) to 1.0 x 10(-3) M for o-cresol. The theoretical detection limits and the relative standard deviations for ten measurements of phenol and o-cresol are 1.125 x 10(-5) M, 1.06% and 4.201 x 10(-5) M, 1.44%, respectively.