REACTIVE SOLVENT-EXTRACTION OF AMINO-ACIDS WITH CATIONIC EXTRACTANTS

A mixture of amino acids (arginine, phenylalanine, alanine, glycine an d aspartic acid) in solution was extracted by four acidic extractants (dinonylnaphthalenesulphonic acid (DNNSA), di(2-ethylhexyl)monothiopho sphoric acid (D2EHPA(S)), di(2-ethylhexyl)phosphoric acid (D2EHPA) and Versatic 10) in toluene. The extractive capacity of the organic phase for the amino acids, using DNNSA, D2EHPA(S) and D2EHPA was found to d ecrease in the order arginine > phenylalanine > alanine > glycine > as partic acid, although at low pH values phenylalanine > arginine occurr ed for D2EHPA(S) and D2EHPA. Separation factors derived for pairs of a mino acids were in the range 2.0 (glycine-aspartic acid) to 20.1 (alan ine-glycine). The extractive and loading capability of the extractants for the amino acids was found to decrease in the order DNNSA > D2EHPA (S) > D2EHPA > Versatic 10, which follows the reverse order of their r espective acid dissociation constants. DNNSA was shown to be a promisi ng extractant for the extraction and fractionation of amino acids. (C) 1998 SCI.