the invention provides uncharged water - soluble silica - adsorbing polymers for suppressing electroendoosmotic flow and to reduce analyte - wall interactions in capillary electrophoresis . in one aspect of the invention , one or more of such polymers are employed as components of a separation medium for the separation of biomolecules , such as polynucleotides , polysaccharides , proteins , and the like , by capillary electrophoresis . generally , such polymers are characterized by water solubility over the temperature range between about 20 ° c . to about 50 ° c ., concentration in a separation medium in the range between about 0 . 001 % to about 10 % , molecular weight in the range of about 5 × 10 3 to about 1 × 10 6 daltons , and absence of charged groups in an aqueous medium having ph in the range of about 6 to about 9 . in one embodiment , polymers of the invention are selected from the group consisting of polylactams , such as polyvinylpyrrolidone ; n , n - disubstituted polyacrylamides ; and n - substituted polyacrylamides . in accordance with the method of the invention , a sufficient amount of polymer adsorbs to the capillary surface to establish a zone of high viscosity that shields the analyte from the wall and impedes the movement of an electrical double layer under an electric field .