Preparative ion-exchange chromatography of challenging protein separations

Experimental studies were performed on two difficult model mixtures; one (bovine/horse heart cytochrome c) exhibiting converging and the other (ribonuclease A /alpha-chymotrypsinogen A) diverging log capacity factor(k')-log salt plots. While step gradient chromatography proved not suited for these classes of separations, both overloaded linear gradient and displacement were efficacious. Induced sample displacement was observed for the convergent case in linear gradient improving performance.