NONLINEAR CHROMATOGRAPHY OF BETA-LACTOGLOBULIN-A AND BETA-LACTOGLOBULIN-B - NON-LANGMUIRIAN BEHAVIOR

The chromatographic retention and wave characteristics of beta-lactogl obulins A and B were studied experimentally for various nonlinear chro matographic modes of operation, including isocratic and gradient eluti on and frontal and displacement chromatography. In contrast to typical Langmuirian behavior, beta-lactoglobulins A and B show increasing ret ention times with increasing column loading and diffuse fronts and sha rp rears at moderate injection volumes. At higher injection volumes, t he retention times increase initially and then drop. Significant taili ng fronts are found in frontal chromatography, and the displacement ef fect is observed at high feed concentrations. The unusual behavior for both modes of overloaded chromatography has been explained consistent ly with an S-shaped isotherm model. The displacement chromatography of these non-Langmuirian adsorbates has also been analyzed. Serious tail ing of displacement trains is observed, and, consequently, resolution is severely affected. The cause of non-Langmuirian behavior is postula ted to be aggregation of adsorbed proteins on the stationary phase.