Study on Binding Characteristics of Aminocarboxyl Chelating Ligands for Metal Ions

The feasibility of frontal chromatography for determining the complexation stability constant K-ML and total mole of binding site Lambda(0) was demonstrated by the accuracy and precision binding experiments between metal ions (Cu2+, Ni2+ and Co2+) and chelating ligand (IDA), in which R-2 > 0. 98 and RSD < 5%. To further prove the universality of the frontal chromatography, the changing rules of K-ML values between Cu2+, Ni2+, Co2+ and IDA, Asp, L-Glu were examined under NaAc-HAc, Na-PB and Tris-HCl buffer systems. The results showed that the binding strength of chelating ligands for metal ions followed IDA > Asp > Glu; binding strength of metal ions for chelate ligands followed Cu2+ > Ni2+ > Co2+; and the binding effect with NaAc-HAc buffer was the best. In aqueous solution, quantum computing of binding energy (Delta E) and gibbs free energy (Delta G) between chelating ligand and metal ion was performed at the M06/6-311++ G (d, p) level. According to Delta E and Delta G, the binding rules between chelating ligand and metal ion were predicted theoretically. These rules were basically in agreement with above experimental results. The present work provided effective method for studying on binding characteristics of metal ions for aminocarboxyl chelating ligands, thus exhibited a good foundation for improving the stability of immobilized metal affinity chromatographic column and solving the leakage of metal ions from the column in the process of competitive elution.