Polymeric membrane phosphate sensitive electrode based on binuclear organotin compound

Binuclear organotin compounds incorporated in solvent polymeric membranes can act as carriers for phosphate ions. A poly(vinyl chloride) membrane containing bis(tribenzyltin) oxide, o-nitrophenyl octyl ether as plasticizer showed Nernstian response for hydrogen phosphate in the 5 × 10−6–10−1 mol 1−1 activíty range with a slope of −30.1 mV dec−1 in solutions of pH 7.20 ± 0.02. The electrode displayed the following selectivity sequence: HPO42− > I− > Br− > NO3− > Cl− > Ac− > SO42−, which was not in accordance with the Hofmeister series. Also included is the comparison of potentiometric response characteristics between the binuclear and mononuclear organotin compounds. An enhanced response towards HPO42− for the binuclear compound based electrode was observed, showing that binuclear organometallic compounds may become a promising class of carriers for anions.