LARGE-VOLUME STACKING FOR QUANTITATIVE-ANALYSIS OF ANIONS IN CAPILLARY ELECTROPHORESIS .1. LARGE-VOLUME STACKING WITH POLARITY SWITCHING

Several methods have been reported describing on-column concentration for sensitivity enhancement in high-performance capillary electrophore sis. One technique of interest consists of a large-volume hydrodynamic injection, followed by the removal of the large plug of low conductiv ity sample matrix out of the capillary using polarity switching. In th is work the performance of this method is evaluated for the separation of arsenious acids and a comparison is made between the increase in p eak area and peak height to evaluate the real sensitivity enhancement. Finally, the use of this stacking procedure for quantitative analysis is discussed.