Metal-chelating chitin derivatives via reaction of chitosan with nitrilotriacetic acid

Chitosan was cross-linked to various extents with nitrilotriacetic acid in the presence of a water-soluble carbodiimide in homogeneous solution, and was then fully N-acetylated. The structure of the nitrilotriacetic acid residues attached to the chitin backbone was determined by acid-base titration. It was shown that the chitin derivatives contained both iminodiacetate and iminomonoacetate residues which form 1:1-type complexes with copper ions. The chitin gels obtained swelled reversibly with water and behaved like ampholytic cross-linked resins in aqueous solutions of acids and bases.