Speciation Studies of Copper Complexes with L-Glutamic Acid by Using Diethylaminoethyl Sephadex A-25 Column

抄録

A method to evaluate the complexing ability of copper(II) with L-glutamic acid was studied using a weak-base anion exchanger, diethylaminoethyl Sephadex A-25 (A-25). The species of copper(II) complex with L-glutamic acid were Cu(Glu)⁰(1:1 complex) and Cu(Glu)₂^2-(1:2 complex). The 1:2 complex was retained on A-25 since this complex was anionic. The amount of copper retained on A-25 as a 1:2 complex and that which flowed out as free copper(II) ion and a 1:1 complex were determined by flame atomic absorption spectrometry. From the concentration of the 1:2 complex measured, the equations to calculate the stability constants (β₁ and β₂) were derived in terms of the equilibria of the solution; the stability constants obtained were in good agreement with values in the literature. The distribution curves of copper species at various pH were also in good agreement with curves simulated from the estimated stability constants.