UPTAKE OF HYDROPHOBIC AMINO-ACIDS AND SODIUM-CHLORIDE BY A STRONG CATION-EXCHANGER - APPLICATION TO DESALTING AND SEPARATION BY PREPARATIVELIQUID-CHROMATOGRAPHY

The uptake of sodium chloride, leucine and phenylalanine by a strong c ation-exchange resin in the sodium form have been compared. Sodium chl oride was excluded from the resin, as indicated by its parabolic upwar ds curved isotherm, and the corresponding desorption edge was sharpene d (constant pattern). Isotherms for both amino acids constructed from a single elution experiment displayed slightly downwards curvature; th e corresponding desorption edges spread in contrast to the breakthroug h ones. The affinities of both amino acids for the resin were higher ( from 15 to 40 %) in the presence of 1 M sodium chloride, indicating th at hydrophobic interactions played a significant role in the mechanism of sorption. As expected from the isotherms, a mixture of 1 M sodium chloride, leucine and phenylalanine was separated with satisfactory re covery of both amino acids for a column loading of 10 % of the bed vol ume. Real mother liquors have also been separated under the same condi tions.