Simultaneous quantification of dopamine, 5-hydroxytryptamine and four metabolically related compounds by means of reversed-phase high-performance liquid chromatography with electrochemical detection.

A method for simultaneously quantifying dopamine, 5-hydroxytryptamine (5-HT) and four metabolically related compounds has been developed, permitting more efficient neurochemical examination of these often interrelated biogenic amine systems. The method uses high-performance liquid chromatographic separation of these compounds on a C18 reversed-phase column with a buffered mobile phase containing methanol as an organic modifier and heptanesulfonate as an ion-pair reagent. Using 5-hydroxy-N-methyltryptamine as an internal standard and electrochemical detection, chromatography time is less than 12 min. Sample preparation simply involves the addition of internal standard, homogenization in the mobile phase, centrifugation and injection of the supernatant into the chromatograph. The method is sensitive to a tissue content of these compounds of less than 1 ng. The utility of this method for neuropharmacological--neurochemical studies is illustrated with studies using inhibitors of monoamine oxidase (pargyline) and aromatic amino acid decarboxylase (RO 4-4602).