THE ASSAY OF FREE POTASSIUM IN BIOLOGICAL BUFFERS WITH A K+-SELECTIVE GLASS-ELECTRODE

• Type: Article in International Scientific Journal
• Date: 1992

Authors

cabral, jps (Author) FCUP

Journal

Title: Chemical Speciation and Bioavailability

Vol. 4

Pages: 69-74

ISSN: 0954-2299

Publisher: Taylor & Francis

Indexing

ISI Web of Knowledge - 3 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-001-PD9

Abstract (EN): The performance of the Kent K+-selective glass electrode in several biological buffers at neutral pH was evaluated in terms of Nernstian response, repeatability, response time and selectivity. The electrode exhibited a linear response between 2 x 10(-5) to 5 x 10(-4) and 10(-2) M K+, with a slope of 54.9-63.1 mV per decade change in K+ activity. In successive calibrations in the range of 10(-5) to 10(-2) M K+, the coefficient of variation of the potential in a given K+ concentration decreased with increasing K+ concentration, and was lower than 5%, indicating that in this range of concentrations, the electrode exhibited good repeatability. The response time for a sudden tenfold increase in K+ concentration was 1.3-3.6 min for 10(-5) M, and 0.5-1 min for 10(-4) M K+. The influence of Ca2+ and Mg2+ on electrode. potential was very small, but Na+ and H+ strongly interfered with electrode response. The selectivity coefficient K+/Na+ was 0.11 and K+/H+ 3.8. The results suggested that in several biological buffers containing no Na+ and with neutral pH, the K+-selective glass electrode can be used to assay with accuracy and rapidity free potassium in the range of 10(-5) to 10(-2) M, being therefore an alternative to valinomycin-based electrodes.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6