Determination of silver(I) by cyclic voltammetry at iodine-coated electrodes

Abstract

Voltammetric investigations on iodine-coated platinum electrodes have revealed their remarkable inertness towards molecular adsorption, which means suppression of surface processes, interferences and generally the current background in voltammetric measurements. Iodine-coated platinum electrodes were prepared by potentiostatic adsorption of iodine at 0.20 V from 1 mmol l^–1 KI solution in 0.5 mol l^–1 H₂SO₄. The passive potential window (the working potential range) in 0.5 mol l^–1 H₂SO₄ is approximately from –0.10 to 0.95 V. Voltammetric measurements of Ag⁺ on the iodine-coated electrode revealed the existence of a linear relationship between the anodic peak current and the bulk concentration of silver ions. The detection limit was 5.7 × 10^–6 mol l^–1. The calibration graph had a slope of 7.58 × 10⁵µA mol^–1 l over a working range from 1 × 10^–5 to 1 × 10^–3 mol l^–1 with a correlation coefficient of 0.9997.