Application of the split-peak effect to study the adsorption kinetics of human serum albumin on a reversed-phase support

Non-linear elution effects in split-peak chromatography. II. Role of ligand heterogeneity in solute binding to columns with adsorption-limited kinetics

The split-peak effect is a useful phenomenon in studying the kinetic behavior of chromatographic supports. This work examined the combined role of ligand heterogeneity and non-linear elution conditions (i.e., sample load dependence) on the solute free fractions that are measured during split-peak studies. Exact expressions were derived to describe the effects of ligand heterogeneity under linear elution conditions, and simulation models were developed to specifically examine the combined effects of ligand heterogeneity and non-linear elution in systems with adsorption-limited rates for solute binding. The simulations showed that ligand heterogeneity increased the amount of free solute seen at any flow-rate or sample size, with this being most noticeable when using low flow-rates or large samples. One application in which these increases were examined in detail concerned the use of the split-peak effect for association rate constant measurements. It was found that linear extrapolation methods developed for homogeneous systems (as a correction for non-linear elution conditions) could successfully be applied to columns containing heterogeneous ligands. Columns containing immobilized protein A and/or protein G were used as experimental models to test the validity of the simulations; the behavior of these columns showed good quantitative and qualitative agreement with the predicted theoretical results.

Kinetic study of the adsorption of human serum albumin on immobilized antibody using the split-peak effect in immunochromatography

The split-peak effect was used to determine the association rate constant of the antigen-immobilized antibody reaction. The amount of immobilized human serum albumin antibody on the chromatographic support was varied in order to find the optimal conditions to reduce the mass transfer contribution in the stagnant mobile phase fluid and measure the effective association rate constant of human serum albumin with the immobilized antibody. Kinetic studies as a function of flow-rate demonstrate the validity of the method consisting in determining the association rate constant from measurements performed on columns of various capacities. These experiments show that limitations due to mass transfer to the surface of the adsorbent are minimized at high flow-rates and for a low density of immobilized ligand.