A Samarium (III) Selective Electrode Based on Zirconium (IV) Boratophosphate

A samarium(III) selective potentiometric sensor has been prepared on the basis of polyvinyl chloride (PVC) membranes containing an ion exchanger (zirconium boratophosphate) as an electro-active material. The best performance was exhibited by a membrane having the following composition: zirconium boratophosphate (10%) and poly vinylchloride (90%). This membrane works well over a wide concentration range (from 1 × 10^?5 to 1 ? 10^?1 M) of Sm(III) ions with a Nernstian slope of 20.2 mV/decade. The response time of the sensor is 15 s, and the membrane can be used for more than six months with good reproducibility. Selectivity coefficients determined by the fixed interference method for a number of mono-, di-, and trivalent cations are reported. The sensor has also been used as an indicator electrode in the potentiometric titrations of samarium (III) ions with EDTA solution.