INTERFACIAL EFFECTS IN SIZE-EXCLUSION CHROMATOGRAPHY OF LATEX

The retention volume in size-exclusion chromatography (SEC) depends on both the size of the particle proper and the interfacial mutual repulsion of the surfaces, i.e., between the pore wall and the surface of the particles. The presence of some interfacial repulsion is crucial to obtain a pure SEC mode of elution. It is therefore always present and should not be neglected as is usually done. Analysis of published data shows that the interfacial repulsion is well described by the Dejaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability, and its properties can therefore be studied in detail via chromatography. It is shown that interfacial repulsion depends on the size of the latex beads ans attains large values for larger beads. For a given size of the bead it depends strongly on its charge up to a limit of saturation, as predicted by DLVO theory.