Performance of carbohydrate-modified fused-silica capillaries for the separation of proteins by zone electrophoresis.

The walls of fused-silica capillaries were chemically modified with small carbohydrate moieties in order to diminish the wall adsorption of proteins in capillary zone electrophoresis. A diol-type coating, prepared by bonding of gamma-glycidoxy propyltrimethoxysilane to the wall followed by acidic hydrolysis, shows for proteins a similar electrophoretic behaviour as various pH values to a polyethylene glycol (PEG) coating tested previously. Although good peak shapes were obtained for proteins in the pH range 3-5, the efficiency on the diol coating is worse than that on the PEG coating. At higher pH values the peaks are deformed and the efficiency is lost. A maltose coating appears to shield the silica surface well for proteins up to pH 7. The peak shapes of proteins are acceptable, but the efficiency of the maltose coating is smaller than that on the diol coating. The diol coating is stable in the indicated pH range. However, with the maltose coating good stability is obtained only on adding an antimicrobial agent to the buffers.