Abstract

A new modified carbon paste electrode (CPE) based on a recently synthesized Schiff base complex of Fe(III) as a suitable carrier for I⁻ ion is described. The electrode exhibits a super Nernstian slope of 71.0±0.3 mV per decade for I⁻ ion over a wide concentration range from 1.0×10⁻⁶ to 5.0×10⁻¹ M, with a low detection limit of 6.5×10⁻⁷ M. It has a relatively fast response time, a satisfactory reproducibility and relatively long life time. The proposed sensor shows a fairly good selectivity toward I⁻ ion in comparison to other common anions. The potentiometric response is independent of the pH of the test solution in the pH range 3.5–10.0. Spectrophotometric studies confirmed the redox-type response mechanism of the electrode toward iodide ion. The proposed electrode was used as an indicator electrode in potentiometric titration of iodide ion.