Detection by HPLC-EC of primary amines recovered in aqueous push-pull perfusates from cat cuneate nucleus

A method is described for the quantitative detection of primary amines - particularly free amino acids - recovered in aqueous push-pull perfusates obtained from the cat cuneate nucleus. Isoindole derivatives of primary amine groups are formed by precolumn reaction with o-phthalaldehyde and mercaptoethanol. Derivatized sample components are separated and detected using HPLC with electrochemical detection. Of 22 amino acids standards studied individually, 12 were detectable under the conditions described. Variability of elution times and detector output peak heights were less than 2% and less than 10%, respectively. Concentration curves were linear to the 10 picomole order of magnitude. For cuneate nucleus perfusates, samples recovered during continuous peripheral somatosensory stimulation contained detectable derivative levels elevated above those of control samples. Sources of error in data interpretation are discussed.