[The distribution space of physically dissolved oxygen in aqueous solutions of organic substances]

In order to evaluate the distribution of molecular oxygen in biological systems, the oxygen solubility (ml/ml atm) at 37 degrees C in aqueous solutions of thirty organic substances with different concentrations was measured by the classical Van Slyke principle. The oxygen solubility always (with the exception of hemoglobin) decreases exponentially with increasing concentration of the respective substance. In all cases this behavior is described highly significant by a simple empiric exponential function, when the substance concentration as well as the oxygen solubility of pure water is given. The influence of one substance on oxygen solubility contributes additively to the over-all solubility value of a solution of several dissolved substances. Changes in oxygen, solubility and, therefore, oxygen distribution in aqueous solutions may be related to three main phenomena: 1. restriction of the free water volume by the specific partial volume of a dissolved substance (e.g. urea solutions), 2. existence of non-solvent water for oxygen especially in solutions of amino acids), 3. adsorption of oxygen at the interphase in a heterogenous system (e.g. protein solutions).