Simultaneous measurement of 5-hydroxytryptophan and L-dihydroxyphenylalanine by high-performance liquid chromatography with electrochemical detection. Measurement of serotonin and catecholamine turnover in discrete brain regions.

A sensitive method, using reversed-phase high-performance liquid chromatography with electrochemical detection, which allows the measurement of both 5-hydroxytryptophan and L-dihydroxyphenylalanine is described. This method, used in conjunction with the administration in vivo of an L-aromatic amino acid decarboxylase inhibitor, allows the simultaneous measurement of serotonin and catecholamine synthesis rates in small discrete brain regions.