For the separation of enzyme （ -chymotripsin） the characteristics of affinity chromatography were studied. The system employed Sepharose CL-4B as a gel matrix (a packing meterial), 4-phenylbutylamine as a ligand and -chymotrypsin as a solute.
Moment analysis was used to determine the retention time in a column, in which the longitudinal dispersion in the mobile phase, the radial diffusion inside the porous spherical gel beads and the sorption on the ligands attached to the gel bead were simultaneously taking place.
To analyze the effect of pH on the retention time an ionization model was incorporated into the chromatrgraphic model. Dependence of adsorption equilibrium constant and the retention time on pH were investigated. From the experimental data the approximate pK values could be obtained.