Application of a PVC membrane electrochemical sensor for Determining La3+ based on 4',4''(5'')-Di-tert-butyldibenzo-18 -crown-6 as a novel ionophore

In this study, a new ion-selective electrode for La3+ is described, illustrating 4',4''(5'')-Di-tert-butyldibenzo-18-crown-6 in a poly(vinylchloride) (PVC) membrane with dibutyl phetalat (DBP) as a plasticizer andsodium tetraphenyl borate (NaTPB) as an anionic additive. This sensor presented very good selectivity andsensitivity towards the La3+ ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The proposed electrode exhibited a significantly enhanced response towards the La3+ions across the concentration range of 1.0×10−2 to 1.0×10−6 M for the pH variation from 7 to 11.5 with alower detection limit of 5.6×10−6 M. Moreover, the sensors displayed the Nernstian slope of 20.2±0.5 mVperdecade, having a fast response time within 30 s over the entire concentration range. It could also be used for at least 3 months with no potential divergence. As a result, the coated graphite sensor was successfully applied as an indicator electrode in the potentiometric titration of nickel ion with EDTA and in directdetermination in La3+ ion with EDTA and in direct determination in the potentiometric titration of lantanium(III) ion with sodium chloride solutions with a sharp potential change occurred at the end point.

Application of a PVC membrane electrochemical sensor for Determining La3+ based on 4',4''(5'')-Di-tert-butyldibenzo-18 -crown-6 as a novel ionophore Keywords:

PVC membrane , Ion-selective electrode , Sensor , Potentiometry , 4' , 4''(5'')-Di-tertbutyldibenzo-18-crown-6