Pressurized-flow anion-exchange capillary electrochromatography using a polymeric ion-exchange stationary phase

The feasibility of using capillary columns equipped with silica frits and p acked with a polymer-based anion exchanger (Dionex AS9-HC) for CEC separati ons of inorganic anions has been investigated. Experiments using a conventi onal 25 cm packed bed, and mobile phase how that is a combination of hydrod ynamic and electroosmotic flow were used to demonstrate that by varying the applied voltage (electrophoresis component) or the concentration of the co mpeting ion in the mobile phase lion-exchange component), considerable chan ges in the separation selectivity could be obtained. Using an artificial ne ural network, this separation system was modelled and the results obtained used to determine the optimum conditions (9 mM perchlorate and -10 kV) for the separation of eight inorganic anions. When a short (8 cm) packed bed wa s used, with detection immediately following the packed section, the separa tion of eight test analytes in under 2.2 min was possible using pressure-dr iven flow and a simple step voltage gradient. A more rapid separation of th ese analytes was obtained by only applying high voltage (-30 kV), where man y of the same analytes were separated in less than 20 s and with a differen t separation selectivity to that obtained in conventional ion-exchange or c apillary electrophoresis separations. (C) 2000 Elsevier Science B.V. All ri ghts reserved.