Triiodide Ion-Selective Electrode Based on Charge-Transfer Complex of 4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo-[8.8.8]hexacosane (original) (raw)

Two new highly selective triiodide electrodes have been prepared using charge-transfer complex of iodine with cryptand 222 as an electroactive ionophore and nitrophenyl octyl ether as a plasticizing agent. The electrodes showed Nernstian response to triiodide ions over a concentration range from 1.0´10 -2 -7.9´10 -7 M and from 1.0´10 -2 -1´10 -6 M with detection limits of 6.3´10 -7 and 7.9´10 -7 M for cryptand and its charge-transfer complex with iodine, respectively. The response times (t 95% ) of the sensors were 10 and 5 s. The membrane could be used for more than 1 month without any divergence in potentials. The proposed sensors exhibited very high selectivity for triiodide ion over other anions, and could be used in a wide pH range~2-10. These electrodes were successfully applied as an indicator electrode in potentiometric titration of copper in ore samples.