Amperometric Detection of Catechols in Capillary Zone Electrophoresis with Normal and Micellar Solutions

A recently Introduced system for Interfacing capillary zone eietrophoresis with off-column amperometric detection is demonstrated on small-bore columns with normal and micellar solutions. The use of smaller Inner diameter columns with a carbon-fiber electrochemical detector allows for Increased separation efficiency and decreased detection limits. On a 26-μm-I.d. column, separation efficiencies of greater than 400 000 theoretical plates and subfemtomole detection limits have been obtained for several catechols. In order to enhance the selectivity for nonlonic solutes, micellar solutions were employed to allow separation of solutes based on partitioning Into the micelles. The electrochemistry of neutral and cationic catechols In micellar solutions was examined in order to characterize the usefulness of electrochemical detection with micellar solutions. Amperometric detection with micellar solutions is demonstrated for a mixture of catechols on a 52-μm-I.d. column. Minimum amounts of catechol detected were less than 20 fmoi when using micellar solutions.