Solubility of the Proteinogenic α-Amino Acids in Water, Ethanol, and Ethanol-Water Mixtures

Nathan A. Bowden*, Johan P.M. Sanders, Marieke E. Bruins

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

22 Citations (Scopus)

Abstract

The addition of organic solvents to α-amino acids in aqueous solution could be an effective method in crystallization. We reviewed the available data on the solubility of α-amino acids in water, water-ethanol mixtures, and ethanol at 298.15 K and 0.1 MPa. The solubility of l-alanine, l-proline, l-arginine, l-cysteine, and l-lysine in water and ethanol mixtures and the solubility of l-alanine, l-proline, l-arginine, l-cysteine, l-lysine, 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 ultraperfomance liquid chromatography (UPLC) method yield reliable results. In the case of α-amino acids that convert in solution, only the UPLC method was able to discern between the different α-amino acids and yields reliable results. Our results demonstrate that α-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.
Original languageEnglish
Pages (from-to)488-497
JournalJournal of Chemical and Engineering Data
Volume63
Issue number3
DOIs
Publication statusPublished - 8 Mar 2018

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