Enzymatic determination of potassium in serum

Autor:	M J Peake, M Pejakovic, M N Berry, R D Mazzachi
Rok vydání:	1989
Předmět:	Chromatography medicine.diagnostic_test Potassium Sodium Biochemistry (medical) Clinical Biochemistry Analytical chemistry chemistry.chemical_element Reaction rate chemistry Spectrophotometry Reagent medicine Chelation Hemoglobin Pyruvate kinase
Zdroj:	Clinical Chemistry. 35:817-820
ISSN:	1530-8561 0009-9147
DOI:	10.1093/clinchem/35.5.817
Popis:	This is a kinetic assay for measuring K+ in serum, based on the activation of pyruvate kinase (EC 2.7.1.40) by K+. We eliminated interference from Na+ and NH4+ ions, which also activate this enzyme, by including Na+-binding and NH4+-consuming reagents in the reaction mixture. The assay was developed with and evaluated in the Cobas Fara centrifugal analyzer (and has been used in other kinetic analyzers). Within-run and between-run CVs were less than 1.4% and less than 1.6%, respectively. The reaction rate per millimole of K+ per liter (0.05 delta A/min) was more than double that of the reagent blank (0.02 delta A/min). Results correlated well with those by flame photometry, and interference from bilirubin, hemoglobin, lipids, heparin, and other cations was negligible. This method, in conjunction with a previous method we have reported in which beta-galactosidase is used for measuring Na+ in serum, offers a practical alternative to the use of ion-selective electrodes and flame photometry for measuring these clinically important monovalent cations in high-throughput or "stat" biochemical analyzers.
Databáze:	OpenAIRE
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