Study of conditions for voltammetric determinations of iodine at carbon paste electrodes

Abstract

A method has been developed for the determination of iodine in the form of iodide at a carbon paste electrode (CPE) with tricresyl phosphate as a pasting liquid using differential pulse cathodic stripping voltammetry. The determination is based on the combined preconcentration mechanism of iodide anions from acidic media, probably forming ion-pairs with protonated molecules of a pasting liquid, then oxidizing to iodine at +0.7 V (vs. Ag/AgCl) and extracting onto a CPE. The detection limit of 30 µg l−1 was obtained. The procedure was successfully applied to analyse real samples of mineral water and table salts containing either iodide or iodate. The results were verified by means of reference methods, e.g. ICP-MS technique, recovery determinations and iodometric titrations.