A novel ion selective sensor for promethium determination

This is a first promethium¹⁴⁵ ion-selective sensor based on the comparative study of two Schiff base ligands (X₁ and X₂) as neutral ionophores. Effect of various plasticizers: 2-nitrophenyloctylether (o-NPOE), dibutyl phosphonate (DBP), dioctylphthalate (DOP), tri-(2-ethylhexyl) phosphate (TEHP), dibutyl butylphosphonate (DBBP), chloronaphthalene (CN) and anion excluders: potassium tetrakis (p-chloropheny1) borate (KTpClPB), sodiumtetraphenylborate (NaTPB) and oleic acid (OA) have been studied. The membrane with a composition of ionophore (X₁/X₂):KTpClPB:PVC:o-NPOE (w/w, %) in the ratio of 5:5:30:60 exhibited best performance. The best responsive membrane sensors (8 and 21) exhibited working concentration range of 4.5×10^-7-1.0×10^-2M and 3.5×10^-6-1.0×10^-2M with a detection limits of 3.2×10^-7M and 2.3×10^-6M and Nernstian slopes of 20.0±0.5, 19.5±0.5mVdecade^-1 of activity, respectively. The sensor no. 8 works satisfactorily in partially non-aqueous media up to 10% (v/v) content of methanol, ethanol and acetonitrile. Analytical application of the proposed sensor has been demonstrated in determination of promethium (III) ions in spiked water samples.