A method is described for the direct identification of amino acids and amine-containing compounds from a fully developed neuron in Planorbis corneus as well as cultured pheochromocytoma cells by capillary electrophoresis with napthalene-2,3-dicarboxaldehyde (NDA) derivatization and electrochemical detection. Several compounds have been identified from the Planorbis neuron, including dopamine, glycine, dopa, glutamic acid, and aspartic acid. Quantitation was accomplished through the use of calibration curves. Cellular levels of the compounds ranged from 0.386 to 26.5 fmol. Voltammetry of the NDA products was also examined by scanning electrochemical detection in order to determine whether the technique could be used for peak identification. (C) 1998 John Wiley & Sons, Inc.