EFFECT OF SAMPLE STACKING ON RESOLUTION, CALIBRATION GRAPHS AND PH IN CAPILLARY ZONE ELECTROPHORESIS

For the determination of components present in samples at very low concentrations, large injection volumes have to be applied in order to introduce a detectable amount of the analytes in capillary zone electrophoresis (CZE). To obtain a good resolution, the sample analytes have to be concentrated in narrow bands and therefore sample stacking is often applied. Sample stacking can lead to an increase in the electroosmotic flow and extra peak broadening during the analysis, through which the gain in resolution will be lost. Further, the presence of different electrolytes in the capillary can cause pH shifts. In this paper a model is given for the calculation of migration times of components applying sample stacking, and the effects of sample stacking in CZE on resolution, calibration graphs and pH are discussed.