New PVC-membrane electrode based on charge-transfer inclusion complex between I2 and 1,4,8,11-tetraazacyclotetracdecane for selective determination of I3 − ions

Abstract

A new triiodide ion-selective electrode based on charge-transfer complex of iodine with 1,4,8,11-tetraazacyclotetracdecane as membrane carrier was prepared. The best performance of electrode observed with the membrane having the ligand–PVC–NPOE–NaTPB composition 3.0:33:66:0.5 mg which worked well over a wide concentration range 2.8 × 10−6–1.4 × 10−1 M with a Nernstian slope of 59.6 ± 0.3 mV per decade and a detection limit of 1.2 × 10−6 M. This electrode showed a response time of 25 s and was used over a period of 2 months. The electrode exhibits an anti-Hofmeister selectivity sequence with a performance for triiodide at pH 1.5–10.2. The response mechanism of the electrode was investigated by UV–Vis spectroscopic technique. The electrode was successfully applied as an indicator electrode in the potentiometric titration of ascorbic acid and hydroquinone in drugs.