Synthesis of a Charge-Transfer Complex of (1,3-Diphenyldihydro-1H-Imidazole-4,5-Dione Dioxide) with Iodide and Its Application to the Development of a Highly Selective and Sensitive Triiodide PVC-Membrane Electrode

In this paper, a novel membrane triiodide sensor based on a charge-transfer complex of (1,3-diphenyldihydro-1H-imidazole-4,5-dionedioxime) with iodine (CTCI) as a membrane carrier is introduced. The best performance was obtained with a membrane containing 30% polyvinylchloride (PVC), 63% dibutylphthalate (DBP), 5% CTCI and 2% hexadecyltrimethylammonium bromide (HTAB). The electrode shows a Nernstian behavior (slope of 58.2 ± 0.3) over a very wide triiodide ion concentration range (5.0 × 10 –8 –1.0 × 10 –2 M), and has a low detection limit (4.0 × 10 –8 M). The potentiometric response of the sensor is independent of pH of the solution in the pH range 3.0–9.0. The proposed sensor has a very low response time (<12 s) and a good selectivity relative to a wide variety of common inorganic and organic anions, including iodide, bromide, chloride, nitrate, sulfate, thiocyanate, monohydrogen phosphate, and acetate. In fact, the selectivity behavior of the proposed triiodide ion-selective electrode shows great improvements compared to the previously reported electrodes for triiodide ion. The proposed membrane sensor can be used for at least 6 months without any divergence in its potentials. The electrode was successfully applied as an indicator electrode in the titration of triiodide with thiosulfate ion. DOI: 10.1134/S106193480703015X