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

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 x 10(-6)-1.4 x 10(-1) M with a Nernstian slope of 59.6 +/- A 0.3 mV per decade and a detection limit of 1.2 x 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.