Ligand-Exchange Chromatography of Amino Acids on Copper-Loaded Chitosan

Amino acids are retained on the copper form and on the amino copper form of chitosan, especially aspartic acid, glutamic acid, tryptophan, and cysteine. The best conditions for collection and for elution are in phosphate buffers at pH 7 and 12, respectively. No leakage of copper occurs; the amino acids are recovered as copper complexes with a ratio of 1:2 copper: amino acid. Several advantages of chitosan over the resin Chelex are pointed out; namely, absence of swelling, great copper capacity. hydrophilicity, and porous structure.