Determination of Calcium Fractions of Serum. I. The Separation of Protein-bound and Protein-free Fractions by Means of a Simplified Ultrafiltration Technique

Abstract

An Ultrafiltration procedure without special apparatus and with a simple anaerobic blood-collecting technique is described. All compositional and environmental variables influencing the ultrafiltrability of calcium have been thoroughly investigated. For 55 healthy persons average ultrafiltrable calcium, magnesium and inorganic phosphorus at pH 7.37–7.47 and 37°C were 56, 75 and 101 %, respectively. Strict control of pH, pC0₂ and temperature has resulted in precision and reproducibility of ultrafiltration results comparable to respective serum analyses.

Key Words:

• Calcium ions
• Donnan equilibrium
• magnesium ions
• protein-binding
• serum calcium
• serum magnesium