Salicylate-Selective PVC Membrane Electrodes Based on Tribenzyltin(IV) Phenolates as Neutral Carriers

ABSTRACT

A series of tribenzyltin(IV) phenolates were synthesized and used as anion ionophores for PVC membrane electrodes; these novel electrodes exhibit a linear response towards salicylate and an anti-Hofmeister selectivity pattern with high specificity for salicylate over many common anions. The results show that the behavior of the electrodes is considerably influenced by the structures of the carriers and the experimental conditions. Electrodes based on tribenzyltin(IV) p-nitrophenolate possess the best potentiometnc response characteristics and show a linear log[Sal⁻] vs. EMF response over the concentration range 0.1–3.98×10⁻⁶ mol.L⁻¹ in phosphate buffer solutions of pH 5.38 with a detection limit of 2.51×10⁻⁶ mol.L⁻¹ and a slope of -57.05 mV per decade. The response mechanism was also investigated by use of a.c. impedance and anion transport across liquid membranes. The electrodes were applied to the determination of salicylate in urine samples with satisfactory results.

Key Words:

• Potentiometry
• Salicylate-selective electrodes
• Tribenzyltin(IV) phenolates
• Ionophores