Electrochemical liquid-phase microextraction and determination of iodide in kelp based on a carbon paste electrode by cyclic voltammetry

We describe the coupling of liquid-phase microextraction (LPME) with cyclic voltammetry for the determination of iodine in kelp based on a carbon paste electrode with a mixture of castor oil and ethyl benzoate as the organic binder and extracting agent. The iodide was quickly adsorbed on the micro-liquid membrane covering a graphite powder surface without the influence of an applied potential. The extraction follows a Freundlich adsorption isotherm. The oxidation peak current was proportional to the exponential function of iodide concentration in the range from 10 to 400 mu M. The method is sensitive, selective, simple, convenient, not interfered by chloride or bromide, and was applied to the determination of iodide in kelp with a recovery of 99.0-119.7%.