A Novel Holmium(III) Membrane Sensor Based on N‐(1‐Thien‐2‐Ylmethylene)‐1,3‐Benzothiazol‐2‐Amine

Abstract

A novel plasticized membrane sensor for Ho(III) ions based on N‐(1‐thien‐2‐ylmethylene)‐1,3‐benzothiazol‐2‐amine (TBA) as a neutral carrier was prepared. The best performance was obtained with a membrane composition of 31% PVC, 61% benzyle acetate, 2% sodium tetra phenyl borate and 6% carrier. The electrode exhibits a Nernstian response for Ho(III) ions over a particular concentration range (1.0×10⁻⁵−1.0×10⁻² M) with a slope of 19.7±0.2 mV decade⁻¹. The limit of the detection is 7.0×10⁻⁶ M. The sensor has a response time of <15 s and a useful working pH range of 4.0–9.5. The proposed sensor discriminates relatively well towards Ho(III) ions with regard to common alkali, alkaline earth, and specially lanthanide ions. It was successfully applied as an indicator electrode in a potentiometric titration of Ho(III) ions with EDTA. It was also applied in determination of fluoride ions in a mouth wash preparation. The proposed sensor was applied for the determination of Ho(III) ion concentration in binary mixtures.

Keywords:

• Ho(III)
• ion‐selective electrode
• ISEs
• N‐(1‐thien‐2‐ylmethylene)‐1,3‐benzothiazol‐2‐amine
• potentiometry
• PVC membrane

Acknowledgments

The author thanks the Tehran University Research Council for support of this work.