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Abstract: A new ion-selective electrode for Sm3+ ion is described based on the incorporation of N,N′,N″-tris(4-pyridyl)trimesic amide (TPTA) in a poly(vinylchloride) (PVC) matrix. The membrane sensor comprises nitrobenzene (NB) as a plasticizer, and oleic acid (OA) as an anionic additive. The sensor with the optimized composition shows a Nernstian potential response of 19.8±0.5mV decade−1 over a wide concentration range of 1.0×10−2 and 1×10−6 molL−1, with a lower detection limit of 4.7×10−7 molL−1 and satisfactor applicable pH range of 3.6–9.2. Having a short response time of less than 10s and a very good selectivity towards the Sm3+ over a wide variety of interfering cations (e.g. alkali, alkaline earth, transition and heavy metal ions) the sensor seemed to be a promising analytical tool for determination of the Sm3+. Hence, it was used as an indicator electrode in the potentiometric titration of samarium ion with EDTA. It was also applied to the direct samarium recovery in binary mixtures. [Copyright &y& Elsevier]