Ion-pair extraction and fluorimetric determination of potassium with 18-crown-6 and eosin

A highly sensitive and selective fluorimetric determination of potassium is proposed, based on solvent extraction of the ion-pair formed between a large anion and the cationic complex of K + with a crown ether. Sensitivity is achieved by selection of a highly fluorescent counter-ion of the fluoresce...

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Bibliographic Details
Published in:Talanta (Oxford) 1981-07, Vol.28 (7), p.425-430
Main Authors: Sanz-Medel, A., Gomis, D.Blanco, Alvarez, J.R.Garcia
Format: Article
Language:English
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Summary:A highly sensitive and selective fluorimetric determination of potassium is proposed, based on solvent extraction of the ion-pair formed between a large anion and the cationic complex of K + with a crown ether. Sensitivity is achieved by selection of a highly fluorescent counter-ion of the fluorescein group (eosin). A linear working range from 0.01 to 1 ppm of potassium is obtained, which gives a higher sensitivity than any similar method for potassium determination. The relative standard deviation is 4–5%. Selectivity is achieved by matching the radius of the cavity of the 18-crown-6 to the ionic radius of potassium. The system used is exceptionally selective for extraction of potassium in the presence of alkali or alkaline-earth metal cations. The proposed method has been successfully applied to the determination of potassium in blood serum.
ISSN:0039-9140
1873-3573
DOI:10.1016/0039-9140(81)80062-8