PARAMETERS CONTROLLING THE ELUTION WINDOW AND RETENTION FACTORS IN MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY

The resolution of uncharged compounds in micellar electrokinetic capil lary chromatography (MECC) is influenced by both the elution window an d the retention factors of the compounds. The influence of the electro osmotic mobility and the effective mobility of the micelles on the elu tion window is treated theoretically and the effect of different exper imental conditions on the elution window and the retention factors is determined. Although these variables cannot be controlled independentl y in many cases, the resolution in MECC can be improved by adjusting t he composition of the applied electrolyte system. This is demonstrated for several electrolyte systems with different pH values, ionic stren gths, surfactant concentrations and organic modifier contents. Further , the influence of the applied held strength, capillary surface modifi cations and the alkyl chain length of the surfactant are evaluated.