ELECTROOSMOTIC FLOW SUPPRESSING ADDITIVES FOR CAPILLARY-ZONE-ELECTROPHORESIS IN A HYDRODYNAMICALLY CLOSED SEPARATION SYSTEM

Electroosmotic flow in a hydrodynamically closed capillary zone electr ophoresis (CZE) separation compartment must be minimized to achieve hi gh efficiency CZE separations. A group of eight potential electroosmot ic flow suppressors was investigated in this context for the separatio ns in fluorinated ethylene-propylene capillary tubes. The suppressors included water soluble methylhydroxyethyl derivatives of cellulose, po lyvinylalcohol, polyvinylpyrrolidones and polyethyleneglycols of diffe rent molecular masses and Triton X-100. Methylhydroxyethylcellulose de rivatives and polyvinylalcohol were found to provide the highest separ ation efficiencies for a group of model anions when the electroosmotic flow suppressors were used as the carrier electrolyte additives. Usin g a methylhydroxyethylcellulose coated separation compartment very sig nificant improvements in the separation efficiencies were achieved for polyvinylpyrrolidones and polyethyleneglycols applied in the carrier electrolyte solutions. For example, polyvinylpyrrolidone K 90 applied in this way gave for some of the model analytes the plate height value s approaching those estimated in the calculations as theoretical limit s for our experimental conditions (H approximate to 3.5 mu m). CZE exp eriments with albumin and gamma-globulin showed that the use of methyl hydroxyethylcellulose derivative in the carrier electrolyte solution a t pH=9.2 was effective in eliminating potential disturbances in the se paration efficiencies of the analytes due to adsorption of the protein s. (C) 1997 Elsevier Science B.V.