EVALUATION OF FUNDAMENTAL PROPERTIES OF A SILICA CAPILLARY USED FOR CAPILLARY ELECTROPHORESIS

A model was developed that accounts for the decrease in the electroosmotic flow in a capillary electrophoresis system when the buffer concentration is increased. Important parameters are: the initial charge per unit area at the silica capillary wall, Q(o); a compact layer of molecules of constant thickness d(o) that exists between the capillary wall and the buffer; and the equilibrium constant, K(wall), between the cations in the buffer and adsorption sites on the silica capillary. An excellent fit of an equation derived from the model to experimental results was obtained. Values for the above parameters were determined in a number of different buffers and the effect of pH, buffer composition and column coatings on these parameters was evaluated.