Polymeric membrane salicylate-sensitive electrodes based on organotin(IV) carboxylates

Abstract

Selectivity properties were established for membrane electrodes prepared by incorporating tribenzyltin carboxylates in plasticized polymeric membranes. These electrodes display high selectivity for salicylate with respect to many common anions. An electrode prepared with tribenzyltin octoate, using o-nitrophenyl octyl ether (o-NPOE) as the plasticizer, possesses the best potentiometric response characteristics, including a fast response time. It shows a linear response towards salicylate ions over the concentration range 0.1–5 × 10^–6 mol l^–1 with a slope of –57.5 mV decade^–1 in buffer solutions of pH 5.5. The behaviour of the electrode is considerably influenced by the plasticizer employed and the optimum response appears to result when o-NPOE is present. The electrode was applied to the determination of salicylate in pharmaceutical and urine samples.