Determination of free Ca ion concentrations with an ion-selective electrode in the presence of chelating agents in comparison with calculated values
✍ Scribed by Young S. Kim; George M. Padilla
- Publisher
- Elsevier Science
- Year
- 1978
- Tongue
- English
- Weight
- 429 KB
- Volume
- 89
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
Experimentally determined free Ca ion concentrations, measured with a Caselective electrode, were compared with values calculated with a computer program utilizing stability constants of the chelating agents: NTA, EDTA, and EGTA used to set the free ion concentrations in the range of 10d3 to 10-O M. In the presence of 0.1 M KCI, 2 mM MgCl,, 20 mM Hepes (pH 7.4), 2 mM ATP, 0.1 mM CaCl, (total concentration), and various ligand concentrations the measured free Ca*+ levels were found to be approximately six to seven times greater than the computer-derived values. Apparent stability constants for Ca-ATP, Ca-EDTA, and Ca-EGTA were determined under these experimental conditions.