Durable phosphate-selective electrodes based on uranyl salophenes

Lipophilic uranyl salophenes derivatives were used as ionophores in durable phosphateselective electrodes. The influence of the ionophore structure and membrane composition (polarity of plasticizer, the amount of incorporated ionic sites) on the electrode selectivity and long-term stability were studied. The highest selectivity for H2PO4- over other anions tested was obtained for lipophilic uranyl salophene III (with t-butyl substituents) in poly (vinylchloride)/o-nitrophenyl octyl ether (PVC/o-NPOE) membrane containing 20mol% of tetradecylammonium bromide (TDAB). Moreover, phosphate-selective electrodes based on this derivative exhibited the best long-term stability (2 months). The electrode durability can be improved decreasing the amount of the ammonium salt in membrane to 5mol%.