Continuous electrophoretic separations in narrow channels with postchannel derivatization and laser-induced fluorescence detection

The development of a novel technique utilizing a postchannel gap reactor for derivatization with channel electrophoresis and laser-induced fluorescence detection is described. The reactor is made by creating a gap in the top channel plate. The channel is constructed using 25-μm spacers with a gap of 20-30 μm. A derivatizing reagent is added to the gap and allowed to diffuse into the channel and reacts with the analytes as they migrate past the gap. Separations of amino acids and a protein have been accomplished with naphthalene dicarboxaldehyde/2-mercaptoethanol postchannel derivatization and laser-induced fluorescence detection. A linear response is reported for detection of each analyte tested. Mass detection limits obtained for the amino acids are in the attomole range while that for the protein transferrin is 110 zmol.