Novel detection schemes for the trace analysis of amino acids and peptides using capillary electrophoresis

The ability of the cellular biochemist to understand events occurring in small subsections of an individual cell depends on available analytical techniques. capillary electrophoresis (CE) detection schemes for trace level peptide analysis are characterized: an on-line, multichannel, laser-induced fluorescence system and a post-column radionuclide system. The fluorescence system has picomolar concentration detection limits (and zeptomole mass limits of detection) for tagged amino acids and peptides. Preliminary results are presented for a method to enhance the ability to fluorescently tag low concentrations of amino acids and peptides from neuronal subsections. The procedure takes advantage of the high local concentration of peptides within a synaptic vesicle to enhance the derivatization reaction. The other detection method described involves a post-column S-35 detector to examine methionine or cysteine containing peptides. This system deposits the effluent from the separation capillary onto a membrane treated with a solid scintillator. After drying the membrane, the photon emission is imaged with a solid-state integrating detector. The sensitivity for S-35 labeled components is in the attomole range.