According to the International Union of Pure and Applied Chemists (IUPAC) recommendations [1], “chromatography is a physical method of separation in which the components to be separated are distributed between two phases, one of which is stationary (stationary phase) while the other (the mobile phase) moves in a definite direction.'' Today we also have chromatographic methods whereby the two phases are in countercurrent motion, e.g., the simulated moving bed, the continuous annular chromatography, etc. All chromatographic methods have one thing in common and that is the dynamic separation of a substance mixture in a flow system. Usually the chromatographic separation process takes place in a column packed with the particles of the sorbent (stationary/solid phase). Modem high-performance liquid chromatography (HPLC) uses an extensive arsenal of stationary separative phases that can effectively separate a wide variety of mixtures both of small molecules and of polymeric substances, including most importantly biologicals and biopolymers. According to the modem HPLC theory, the sorbent particles can be regarded as rigid spheres of micrometer size that differ considerably in porosity, i.e., ranging from totally nonporous to flow-through (perfusive) ones.