Fluorescence and radionuclide detection schemes for trace-level peptide analysis in capillary electrophooresis

Detection schemes based on laser-induced fluorescence have greatly improved the measurement sensitivity obtainable with capillary electrophoresis. Several instrumental arrangements have been developed which allow the detection of less than picomolar concentrations of fluorescently-tagged analytes in a nanoliter volume. However, if a peptide is reacted with common fluorescent probes at concentrations several orders of magnitude above this instrumental detection limit, nothing is detected exclamation point The authors report their progress in enhancing trace-level derivatization for neuropeptide samples, including the method of vesicle-fusion and the use of preconcentrator capillaries as on-column reactors. In addition, a unique CE radionuclide detection method is described which involves culturing the neurons in a growing media which include 35S-labeled methionine and post-column radionuclide detector to measure the newly synthesized (radiolabeled) peptides. The progress in derivatizing and detecting trace levels of peptides is presented