Partitioning behavior of amino acids in aqueous two-phase systems with recyclable volatile salts.

As part of an ongoing research effort on aqueous two-phase systems (ATPSs) with volatile salts, this work describes the partitioning behavior of a series of amino acids, namely L-serine, glycine, L-alanine, L-valine, L-methionine, L-isoleucine, and L-phenylalanine, in these systems. The results show that amino acids partition in a similar way in polymer-volatile salt ATPSs and in traditional polymer-salt ATPSs. Increasing amino acid hydrophobicities lead to increasing partition coefficients. Moreover, the common linear relationship between the logarithm of the partition coefficient and the tie line length is observed here as well. Furthermore, the relation between relative partition coefficients and relative hydrophobicities of amino acids in the extraction systems investigated in this work is comparable to that in other extraction systems.