Determination of diffusion coefficients by capillary zone electrophoresis

Abstract

Three peak variance methods for the determination of diffusion coefficients of a group of sulfonamides by capillary zone electrophoresis are described. Each of the methods involves careful selection of the experimental conditions such that the observed variance can be described by the simple Einstein equation involving the diffusion coefficient term. The graphical method yields diffusion coefficient values with better than 4% relative standard deviation, whereas not more than 8% relative standard deviation was obtained for the stopped migration and the low field methods. The latter method, however, is the simplest to perform experimentally and requires the shortest time.