Solubility of xenon in amino-acid solutions

We have measured the Ostwald solubility (L) of 133Xe at 25.0 °C in aqueous solutions of the amino acids: alanine (0–1.8 M), arginine (0–0.9 M), glycine (0–2.1 M), hydroxyproline (0–2.3 M), lysine (0–2.8 M), and proline (0–3.5 M) as well as sucrose (0–2.25 M) and NaCl (0–5.25 M). Over the concentration ranges investigated L decreases, monotonically and approximately linearly, with increasing concentration for amino acids and sucrose. The effect on gas solubility of amino acid in solution can be large, e.g., for 133Xe, we measured L(25.0 °C)=0.1060 in distilled water but L(25.0 °C)=0.055 for a 2.8 M lysine solution. The results can be used to calculate hydration numbers (H), i.e., the number of H2O molecules associated with each solute molecule. The average values of hydration number (H̄) obtained at 25.0 °C are 7.9±0.6 for alanine, 0.2±0.5 for arginine, 8.5±0.6 for glycine, 4.5±0.4 for hydroxyproline, 6.1±1.1 for lysine, 2.0±0.2 for proline, and 3.9±0.7 for sucrose.