Patent ID: 7473801

Claim:
A method for purification of an amino acid from an aqueous solution of an alkali metal salt of the amino acid, comprising: (1) cation exchanging, which comprises subjecting the aqueous solution of the alkali metal salt of amino acid to a desalting purification treatment using a cation exchange resin to obtain an aqueous solution of a crude amino acid, wherein said cation exchanging is carried out using a moving bed type continuous ion exchange apparatus; and (2) anion exchanging, which comprises adsorbing an iminodicarboxylic acid using a weakly basic anion exchange resin, the iminodicarboxylic acid being a coexisting by-product produced together with the crude amino acid, to remove the iminodicarboxylic acid from the resulting aqueous solution of the crude amino acid, wherein the aqueous solution of the crude amino acid is passed over the weakly basic anion exchange resin even after the iminodicarboxylic acid has reached the break through point at which the weakly basic anion exchange resin leaks the iminodicarboxylic acid, such that anion exchanging occurs between the iminodicarboxylic acid and the crude amino acid, thereby recovering any amino acid adsorbed to the weakly basic anion exchange resin.