Sweeping of neutral analytes via complexation with borate in capillary zone electrophoresis

Summary The sweeping concept is extended to capillary zone electrophoresis (CZE) separation of neutral solutes involving complexation with borate. Analogous to the pseudostationary phase in electrokinetic chromatography (EKC), the complexing agent (borate) serves as carrier for sweeping and separation in CZE. Therefore, similar to the retention factor in EKC, the focusing effect in the present system is directly related to the association constant between the analyte and complexing agent. Theoretical and some preliminary experimental studies gerenally suggest that the electrophoretic mobility of the complex and the concentration of the complexing agent affect the resulting length of narrowed zones. Moreover, sweeping using borate is affected by pH since borate complexation is pH dependent. From around 10 to 40-fold improvement in peak heights has been observed experimentally for some neutral test analytes (monosaccharides, catechols, and nucleosides)