Iodide selective membrane electrodes based on a Molybdenum–Salen as a neutral carrier

A new polymeric membrane electrode (PME) and a coated platinum disk electrode (CPtE) based on Schiff base complex of Mo(VI) as a suitable carrier for I− ion were described. The influence of membrane composition, pH and possible interfering anions were investigated on the response properties of the electrodes. The electrodes exhibited a Nernstian slope of 63.0 ± 0.5 (CPtE) and 60.3 ± 0.4 (PME) mV decade− 1 in I− ion over a wide concentration range from 7.9 × 10− 7 to 1.0 × 10− 1 M for CPtE and 9.1 × 10− 6 to 1.0 × 10− 1 M I− for PME. The potentiometric response of the electrodes was independent of the pH of the test solution in the pH range 2.0–8.5 with a fast response time (< 10 s). The process of transfer of iodide across the membrane interface was investigated by use of the AC impedance technique. The proposed sensors were successfully applied to direct determination of iodide in samples containing interfering anions, waste water and as indicator electrodes in precipitation titrations.

► We study new selective membrane electrodes for iodide ions.
► To the best of our knowledge this is the first coated platinum disk electrode of I–.
► The sensors have a wide concentration range with a fast response time.
► Efforts have been made to improve the selectivity with the use of CPtE.