Fused‐silica capillaries with surface‐bound dextran layer crosslinked with diepoxypolyethylene glycol for capillary electrophoresis of biological substances at reduced electroosmotic flow

This report is concerned with the introduction of novel surface modification involving the covalent attachment of branched, high molecular weight dextrans and subsequent crosslinking with polyether chains on the inner surface of fused silica capillaries with the aim of producing hydrophilic capillaries with reduced electroosmotic flow (EOF). Three different molecular mass dextrans, namely 45, 71 or 150 kDa were covalently attached to the capillary surface, and subsequently crosslinked with diepoxypolyethylene glycol (PEG). This chemistry produced stable coating over a wide range of conditions including high and low pH aqueous solutions. Moreover, the various dextran‐PEG‐coated capillaries exhibited reduced electroosmotic flow. These features of the dextran‐PEG coatings were useful for the separations of basic and acidic proteins, and provided high resolution separation for closely related acidic monosaccharides and sialooligosaccharides .