High-performance liquid chromatographic assay of rat-brain dopamine and norepinephrine

A high-performance liquid chromatographic method for the assay of dopamine (DM) and norepinephrine (NE) in rat brain has been developed. 3,4-Dihydroxybenzylamine was added to the sample as an internal standard. The isolated amines and the internal standard were subjected to reaction with fluorescamine, separated liquid chromatographically on a glycol-type gel and determined fluorimetrically. The standard deviation of the method was +/-2.7% for DM and +/-5.3% for NE. The contents of DM and NE in rat brain, with or without administration of a tyrosine hydroxylase inhibitor, as measured by the proposed method were always lower than those obtained by the trihydroxyindole method.