Electrolyte Effects on the Amino Acid Solubility in Water: Solubilitiesof Glycine,L-Leucine,L-Phenylalanine, andL-Aspartic Acid in SaltSolutions of (Na+,K+,NH4+)/(Cl-,NO3-)

The solubilities of glycine,L-leucine,L-phenyl-alanine, andL-aspartic acid in aqueous solutions of the saltscomposed by combining Na+,K+, and NH4+cations and Cl-andNO3-anions were measured up to 2.0 salt molality at 298.2 K bythe analytical gravimetric method. Using these data along with areview of literature information, encompassing all amino acids forwhich solubility is available in the studied aqueous electrolytesolutions, allowed us to interpret the effect of the functional groupsof amino acids on their solubility. The four amino acids studiedhere showed higher solubility in aqueous solutions of salts with thenitrate anion. Except forL-aspartic acid with a polar side chain,amino acids with apolar side chains presented the highest salting-ineffect in aqueous salt solutions with NH4+. The cations Na+and K+did not seem to establish relevant interactions with the amino acids and had little impact on their aqueous solubility.

Automated summary

The solubilities of amino acids in aqueous salt solutions were measured, and the effect of functional groups on solubility was analyzed.