63.
A poly(vinyl chloride) (PVC) membrane sensor for holmium ions was fabricated based on
N‐[(
Z)‐1‐(2‐thienyl)‐ methylidene]‐
N‐[4‐(4‐{[(
Z)‐1‐(2‐thienyl)methylidene]amino} phenoxy)phenyl] amine (TPA) as a new ion carrier, acetophenon (AP) as plasticizing solvent mediator and sodium tetraphenyl borate (NaTPB) as an anion excluder. The electrode shows a good selectivity towards Ho
3+ ions respect to other inorganic cations, including alkali, alkaline earth, transition and heavy metal ions. The constructed sensor displays a Nernstian behavior (19.5±0.3 mV/decade) over the concentration range of 1
.0×10
−6 to 1
.0×10
−2 mol·L
−1 with the detection limit of the electrode being 4
.6×10
−7 mol·L
−1 and very short response time (
ca. 5 s). It has a useful working pH range of 3.2–9.8 for at least 8 weeks. The electrode was successfully applied as an indicator electrode for the potentiometric titration of a Ho
3+ solution with EDTA and holmium determination in some alloys. The proposed sensor accuracy was studied by the determination of Ho
3+ in mixtures of three different ions.
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