RADIOENZYMATIC MICRO-ASSAY FOR SIMULTANEOUS MEASUREMENT OF CATECHOLAMINES AND THEIR DEAMINATED METABOLITES

A simple and specific assay for measurement of norepinephrine, epinephrine, and their major deaminated metabolites 3,4-dihydroxyphenylglycol and 3,4-dihydroxymandelic acid in plasma has been developed. The assay is based on the conversion of these compounds to their O-methylated derivatives in the presence of catechol-O-methyltransferase and S-adenosyl-[methyl3H]methionine. The formed tritiated derivatives are selectively extracted in organic solvents and isolated by thin-layer chromatography. After oxidation to vanillin they are purified by solvent extraction and measured by liquid scintillation spectrophotometry. The assay is rapid and results can be obtained in less than 3 hr. © 1979.