The First Dissociation Constant for Carbonic Acid and the Solubility of Carbon Dioxide in Human Amniotic Fluid

Abstract

Determinations of pK₁' for carbonic acid and of αCO₂ in amniotic fluid were made. PCO₂ and pH were determined with electrodes and CCO₂ with gasometric methods. The mean value of pK₁' was 6.120 ± 0.004 in 39 determinations. The mean value of αCO₂ was 0.824 ± 0.004 at 20°C and 0.537 ± 0.003 at 37°C in 10 determinations at each temperature level. From the solubility coefficient (αCO₂) at 37°C a solubility factor (S) of 0.0311 was calculated.

Key Words:

• Amniotic fluid
• carbon dioxide
• carbonic acid
• dissociation
• solubility