Amino acids partitioning in aqueous two-phase system of polypropylene glycol and magnesium sulfate

The counter-current chromatography method using aqueous two-phase systems, which is a form of liquid–liquid partition chromatography, could be applied for separation of the amino acids. This method needs some information about the partition coefficient of the amino acids in such systems. In this work, partitioning of amino acids d-alanine, l-valine and l-leucine was investigated in aqueous two-phase system of polypropylene glycol (PPG425) + MgSO4 + H2O at 298.15 K. The results showed that increasing the amino acid hydrophobicity lead to a corresponding increase in the partition coefficients and increasing tie line length lead to decreasing partition coefficients. The effect of the pH on amino acids partitioning was also determined. The experimental data are correlated using a modified virial-type model. The comparisons between the correlation and the experimental data reveal a good agreement.