The construction, electrochemical evaluation and application of new electrode selective to the thoron reagent are reported. The electrode incorporates bathophenanthroline iron: thoron ion pair as electroactive sensing material, o-nitrophenyl octyl ether as plasticizer and PVC as support matrix, exhibits a Nernstian response to thoron with a slope of -29.7+/-1 mV per decade in a range of concentration from 1.0x10(-6) to 5.0x10(-2) mol L(-1), a detection limit of 6.0x10(-7) mol L(-1) and fast response time of less than 30 s. The proposed electrode is successfully applied to zirconium ion determination in aqueous samples using indirect potentiometry and the results obtained are compared with those provided by spectrophotometric analysis using thoron as complexing agent.
