a new potentiometric sensor for determination of cesium ion in environmental samples

a new cesium ion selective pvc membrane based on parent calix [4] arene was developed for potentiometric determination of cesium in environmental samples. the electrode based on p-5,11,17,23tetra(tertbutyl) 25,26,27,28-tetrahydroxy calix[4]arene(thc) as ionophor ,dibutyl phthalate (dbp)as plasticizer ,sodium tetra phenyl borate(natpb)and oleic acid as lipophilic salt and additive showed the best performance. the electrode exhibits a good nernstian response in a concentration range of 1×10-1-3.16×10−5 m of cesium, with a slope of 58.5 ± 0.6mv per decade and a detection limit of 1.58×10−5 m.it exhibits a good selectivity for cesium in comparison with alkali, alkaline earth, and some transition metal ions. the electrode response and selectivity remained almost unchanged for more than a month. the effect of membrane composition, ph and concentration of internal solution on the potential response of the electrode were also studied. the applicability of the electrode to real samples was also assessed.