Rapid automated analysis of biogenic amines and their metabolites using reversed-phase high-performance liquid...

A method is described for the rapid automated analysis of: dopamine and norepinephrine; the major dopamine metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid; and the indoles tryptophan, serotonin, and 5-hydroxyindoleacetic acid in less than 0.5 mg of brain tissue. Samples are deproteinized, injected directly onto a reversed-phase high-performance liquid chromatography column, and quantitated using an electrochemical detector with a glassy carbon electrode. High sample stability permits the use of an automatic sample injector at ambient temperatures. Depending upon the column particle size, sample run times are less than 7-12 min. Thus, over 50 duplicate samples can readily be measured in a single day with very little operator attention. The chromatographic system used also resolves epinephrine, and the catecholamine metabolites: 3-methoxytyramine, normetanephrine, and 3-methoxy-4-hydroxyphenylglycol; and with very little modification this assay also could be used to measure these compounds.