Preparation of a Lead Ion-Selective Electrode Based Upon Crown Ether Nitrobenzo18-Crown-6

Nitrobenzo18-crown-6 (nb18c6) has been examined as an ion sensing materialfor fabricating a pvc membrane lead ion-selective potentiometric sensor. the bestperformance of the electrode was observed with a membrane composition formed by 30%pvc, 58.5% ortho-nitrophenyloctylether (npoe) as plasticizing solvent mediator, 9% ofnb18c6 as ionophore and 2.5% sodium tetraphenylborate (natpb) as ion excluder. theelectrode presents a nearly nernstian response (a slope of 30.5±0.5 mv/decade) over aconcentration range 1×10-5-1×10-2 m of lead ions, with a limit of detection 8.9×10-6 m. itspotential response was independent on the ph variation in the range 2.2-4.1. the dynamicresponse time of the electrode to achieve a steady potential was relatively fast and was foundto be about 6 seconds. the selectivity of the prepared electrode relative to some mono-, di-,tri- and tetra-valent metal ions was examined. this electrode can be used for 3 monthswithout considerable divergences in the potential response. it was successfully used as anindicator electrode for the complex formation titration of lead solutions by edta.