Lanthanide Recognition: Determination of Thulium(III) Ions in Presence of Other Rare Earth Elements by a Thulium(III) Sensor Based on 4-Methyl-1,2-Bis(2-Pyridinecarboxamido)benzene as a Sensing Material

Abstract

In this research, a novel thulium(III) potentiometric membrane sensor based on 4-methyl-1,2-bis(2-pyridinecarboxamido) benzene (MPB) is described. The sensor exhibits a Nernstian response over a concentration range of 1.0 × 10^?7 M to 1.0 × 10^?1 M, with a detection limit of 9.0 × 10^?8 M. The best performance was achieved with a membrane composition of 30% PVC, 60% nitrobenzene (NB), 6% MPB, and 4% sodium tetraphenylborate (NaTPB). It was found that at the pH range of 3.6 to 9.0, the potential response of the sensor was not affected by the pH. Furthermore, the electrode presents satisfactory reproducibility, very fast response time (15 s), and relatively good discriminating ability for Tm(III) ions with respect to many common cations and lanthanide ions. The validation of the proposed electrode was tested by using Coal and Fuel Ash (FFA 1 Fly Ash) as a Certified Reference Material (CRM).