Optimization of selectivity in capillary zone electrophoresis via dynamic pH gradient and dynamic flow gradient

Two different techniques, dynamic pH gradient and electroosmotic flow gradient, were introduced to control selectivity in capillary zone electrophoresis. These two types of gradients showed dramatic effects on the resolution of organic acids. Dynamic pH gradient from pH 3.0 to 5.2 is readily generated by a high-performance liquid chromatography gradient pump. Electroosmotic flow gradient is produced by changing the reservoirs containing different concentrations of cetylammonium bromide for injection and running. The two gradient techniques are applied to the separation of model anions which are not resolved at constant pH or at constant flow conditions.