Polymeric membrane and coated graphite samarium(III)-selective electrodes based on isopropyl 2-[(isopropoxycarbothioyl)disulfanyl]ethanethioate

Abstract

New polymeric membrane (PME) and coated graphite (CGE) samarium(III)-selective electrodes were prepared based on isopropyl 2-[(isopropoxycarbothioyl) disulfanyl]ethanethioate as a suitable neutral ionophore. The electrodes exhibit Nernstian slopes for Sm 3+ ions over wide concentration ranges (1.0×10 −5 to 1.0×10 −1 M for PME and 1.0×10 −6 to 1.0×10 −1 M for CGE). The PME and CGE have limits of detection of 3.1×10 −6 and 5.0×10 −7 M, respectively, and response times of about 20 s. The potentiometric responses are independent of the pH of the test solution in the pH range 4.0–7.0. The proposed electrodes revealed good selectivities over a wide variety of other cations including alkali, alkaline earth, transition and heavy metal ions. The electrodes were successfully applied to the recovery of Sm 3+ ion from tap water samples and also, as an indicator electrode, in potentiometric titration of samarium(III) ions.