Tetraphenylborate-Selective Coated Wire Electrode Based on Tetraphenylborate-Alkyltriphenylphosphonium Derivatives

A coated wire electrode selectively sensitive to tetraphenylborate ion(TPB−) based on an ion-pair complex of TPB− ion with alkylriphenylphosphonium derivatives was prepared with poly(vinyl chloride)-membrane plasticized with o-nitrophenyloctyl ether. The electrodes responded with Nernstian slopes (ca. 58 mV/decade) over a concentration range of 2x10−7-10−2 M. A change in pH did not affect the electrode performance within the range of pH 5.5-12. The electrodes exhibited very good selectivity for TPB− ion against other organic and inorganic anions. The reproducibility, stablity, response time and lifetime of the electrode were studied. The electrode was used to determine benzalkonium and zephiramine in a bactericidal solution with sodium tetraphenylborate as a titrant.