POSTCOLUMN DERIVATIZATION IN NARROW-BORE CAPILLARIES FOR THE ANALYSISOF AMINO-ACIDS AND PROTEINS BY CAPILLARY ELECTROPHORESIS WITH FLUORESCENCE DETECTION

The construction and performance of a post-column reactor for capillar y electrophoresis with laser-induced fluorescence detection in 10 mum i.d. capillaries is described. The post-column reactor is based on a g ap design and relies primarily on diffusion for addition and mixing of derivatizing reagents. Reactors with gaps of 4 to 160 mum are easily built with minimal micromanipulation between two 10 mum i.d. capillari es. Optimal separation efficiencies and sensitivities are obtained wit h gaps of less than 10 mum. Separations of amino acids and proteins wi th o-phthaldialdehyde/2-mercaptoethanol post-column derivatization and laser-induced fluorescence detection are shown. Linear detector respo nse is found for amino acids and proteins, and peak efficiencies as hi gh as 230,000 theoretical plates are obtained for some analytes. The u se of relatively small columns for capillary electrophoresis results i n a separation and detection system that produces very low mass detect ion limits for biological molecules from picoliter sample injections. Mass detection limits of 130 and 5.2 attomoles are obtained for glycin e and human transferrin, respectively.