A new ytterbium(III) PVC membrane electrode based on 6-methy-4-{[1-(1H-pyrrol-2-yl)methylidene]amino}-3-thioxo-3,4dihydro-1,2,4-triazin-5(2H)-one

This study presents the development of an original electrode, employing 6-methy-4-{1-(1H-pyrrol-2-yl)methylidene]amino}-3-thioxo-3,4dihydro-1,2,4-triazin-5(2H)-one (PMTO) as a suitable ionophore. Interestingly, the electrode performance provided a very good response for Yb³⁺ in a wide concentration range (from 1.0 × 10⁻⁶ to 1.0 × 10⁻¹ mol L⁻¹) with a detection limit of 4.6 × 10⁻⁷ mol L⁻¹ and a slope of 19.5 ± 0.3 mV per decade of Yb³⁺ concentration. Furthermore, it possessed a fast response time of about 10 s and it functioned in the pH range of 3.3-8.0 with a usage of at least 2 months without observing any deviations. Noticeably, the proposed electrode revealed an excellent selectivity for Yb³⁺ over a broad variety of alkali, alkaline earth, transition and heavy metal ions. The practical applicability of the electrode was demonstrated by its utilization as an indicator electrode in the potentiometric titration of Yb³⁺ ions with EDTA and in the determination of F⁻ in mouth wash samples. Additionally, it was also applied for the determination of Yb³⁺ ions in binary mixtures.