Determination of Iodates Using Silver Solid Amalgam Electrodes

Use of the polished solid silver amalgam electrode (p-AgSAE) as such and of its modification by a mercury meniscus (m-AgSAE) for determination of iodates in aqueous solutions by differential pulse cathodic voltammetry is described. The former type of the mentioned electrode does not contain free mercury and is of a completely non-toxic form. The determination is based on reduction of iodates into iodides in 0.1 M NaOH at the peak potential about −1.3 V (vs. SCE). The detection limit (3 SD; N=11) for p-AgSAE is 0.34 ppm iodine, RSD=1.2% and for m-AgSAE 0.14 ppm iodine, RSD=0.5% respectively. The range of possible working potentials of both types of AgSAE is presented, in comparison with the hanging mercury drop electrode. The described method of the determination of iodine in the form of iodates in commercial table salt was found to be simple and ready for common applications.