Triiodide PVC Membrane Electrode Based on a Charge-Transfer Complex of Iodine with 2,4,6,8- Tetraphenyl-2,4,6,8-tetraazabicyclo[3.3.0]octane

A novel triiodide ion-selective electrode based on a charge-transfer complex of iodine with 2,4,6,8-tetraphenyl-2,4,6,8-tetraazabicyclo[3.3.0]octane as membrane carrier was prepared. The electrode has a linear dynamic range between 5.0 × 10-2 and 3.5 × 10-6 M, with a near-Nernstian slope of 54.7 ± 0.8 mV decade-1 and a detection limit of 2.0 × 10-6 M. The potentiometric response is independent of the pH of the solution in the pH range 4.0−10.5. The electrode possesses the advantages of low resistance, short conditioning time, fast response, and, especially, very good selectivities over a wide variety of other anions. The electrode can be used for at least 10 months without any considerable divergence in potentials. It was used as an indicator electrode in potentiometric titration of triiodide ions.