Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The addition of organic solvents to a-amino acids in aqueous solution could be an effective method in crystallization. We reviewed the data available on the effects of ethanol on the solubility of a-amino acids. The solubility of L-cysteine in water, the solubility of L-alanine, L-proline, L-arginine, L-cysteine, L-lysine and L-methionine in water and ethanol mixtures and the solubility of L-alanine, L-proline, L-arginine, L-cysteine, L-lysine, Lmethionine, L-asparagine, L-glutamine, L-histidine and L-leucine in pure ethanol systems were measured and are published here for the first time. The impact on the solubility of amino acids that can convert in solution, L-glutamic acid and L-cysteine, was studied. At lower concentrations, only the ninhydrin method and the UPLC method yield reliable results. In the case of a-amino acids that convert in solution, only the UPLC method was able to discern between the different a-amino acids and yields reliable results. Our results demonstrate that a- amino acids with similar physical structures have similar changes in solubility in mixed water/ethanol mixtures. The solubility of L-tryptophan increased at moderate ethanol concentrations.