Displacer concentration effects in displacement chromatography: Implications for trace solute detection

In this paper, the utility of ion-exchange displacement chromatography for the concentration and enrichment of trace proteins is examined. Separations with varying displacer concentrations (1–25 mM neomycin sulfate) indicate that higher concentrations result in elevated protein concentrations, at the price of reduced yields. The results demonstrate that displacement chromatography carried out at relatively low displacer concentrations (2.5 mM) can produce significant concentration (8.5-fold) and enrichment (18-fold) of trace proteins present in the feed. Parametric simulations using the steric mass action model are carried out to investigate the concentration effects and enrichment factors observed over a wide range of feed, displacer and buffer counter-ion concentrations, and solute separation factors. The simulations confirm that trace components can be readily concentrated and enriched by displacement chromatography and that these effects will be more pronounced as the separation factor between trace and abundant components is increased. The results presented in this paper indicate the potential of displacement chromatography for improved separations where trace enrichment is critical such as proteomic applications.