Abstract
A theoretical description of the influence of electroosmosis on the effective mobility of simple ions in capillary zone electrophoresis is presented. The mathematical equations derived from the space-charge model contain the pKa value and the density of the weak acid surface groups as parameters characterizing the capillary. It is shown how the zeta potential of the capillary and the effective mobility of typical anions are affected by the pH and ionic strength of the background electrolyte. Furthermore, the model is also used to analyze experimental results on the pH dependency of the electroosmotic mobility in a fused silica capillary, yielding estimates for the pKa values of two types of silanol groups and the total surface density of these groups . With these estimated values for the properties of the silanol groups, the model predictions of the effective mobility are compared with literature data.
Published Version
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