Study Of The Mass Transfer Kinetics In Membrane Affinity Chromatography And Column Reversed-phase Liquid Chromatography

Kinetic studies of mass transfer in chromatography provide essential informationon the separation mechanisms. In this doctoral dissertation, by using nonlinearchromatographic models, the mass transfer kinetics in membrane affinitychromatography (MAC) and reversed-phase liquid column chromatography (RPLC)were discussed.The mass transfer kinetics in the loading stage of MAC were discussed byassuming membrane stack configuration. First, an ideal adsorption (IA) model wasproposed to explore the influence of factors, such as the ligand capacity and thebinding specificity, on the performance of affinity membranes. Then, a Multi-plate(MP) model was derived from it. Together with the lumped kinetic (LK) model, theMP model was used to study the effects of experimental factors, such as flow rate,the thickness of the membrane stack and protein concentration, on the performance.An elution curve (EC) model was proposed for the elution stage of MAC. Theanalytical solution of this model obtained by ignoring the effect of axial dispersionshows that the height of the elution peak decreases with increasing flow rate. Byfitting experimental data to the EC model using a nonlinear fitting procedure, it wasfound experimentally that flow rate had significant effect on the axial dispersion andthe mass transfer of the solute between the mobile and stationary phases.The influence of the concentration of caffeine on the chromatographicperformance of reversed-phase column was studied by using the staircase method offrontal analysis. It was shown that the mass transfer kinetics were fast. Theconcentration of caffeine turned out to have little effect on the performance withinthe range below the concentration of about 0.8 mg/mL. Beyond this range, theperformance changed significantly with increasing concentration. By using theequilibrium-dispersive model, the profiles of elution peaks obtained by the pulsemethod could also be well predicted. By using Chem3D with Visual Basic for Application (VBA) in Microsoft Excel,the possible most stable conformations of trehalose and lipid A were discussed. Thismethod makes it possible for researchers to make use of Chem3D according to theirown demands. It will be used in future work to study from microscopic view theseparation mechanisms in chromatography.