The partially neutralized poly(ethylenimine)-grafted Sepharose FF

FF-PEI-R440

exhibited higher protein capacity and faster uptake rate than its starting resin FF-PEI-L740. In this work

the influence of counterions on protein adsorption onto and elution from the FF-PEI-R440 resin was investigated with sodium salts of SCN-

Cl-

HPO42- and SO42- at ionic strengths of 0.03 mol·L-1 and 0.06 mol·L-1. It was found that the static adsorption equilibrium of FF-PEI-R440 was significantly influenced by the counterions

and the adsorption capacity increased in the order of SCN- < SO42- < HPO42- < Cl- at the two ionic strengths. At the low ionic strength

the counterions had no significant effect on the uptake rate and dynamic binding capacity except for SCN-. At high ionic strength

the uptake rate increased in the order of SCN- < SO42-≈Cl- < HPO42-. Dynamic binding capacity increased in the order of SCN- < SO42- < HPO42- < Cl-

the same of the order of adsorption capacity. The dynamic binding capacity kept the highest values when Cl- existed at the two ionic strengths. Protein elution was little affected by counterions. The results indicated that the adsorption performance of FF-PEI-R440 was affected by counterions and the Cl- was the most favorable couterion for column operation.