The fluorimetric estimation of adrenaline and noradrenaline in plasma

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Abstract
Catechol compounds were extracted from bovine and human plasma by passage through columns of alumina and elution with dilute acid. The eluates were separated into basic and non-basic fractions by passage through cation-exchange resins. The purified basic fraction was studied by paper chromatography, paper electrophoresis or bioassay. At every stage of the procedure samples were analysed by two fluorimetric methods. The basic fraction accounted for the catechol compounds present in the alumina eluates. Acid catechols, neutral catechols and 3:4-dihydroxyphenylalanine therefore do not occur in plasma. The estimates of epinephrine and norepinephrine obtained by direct fluorimetric assay agreed with the amounts recovered from the expected positions on paper after electrophoresis and after chromatography in two different solvent systems. There was no evidence for the presence of 3-hydroxytyramine. If epinephrine and norepinephrine are the only catechol compounds in plasma, the two fluorimetric methods used should yield identical results. A high degree of correlation was indeed found consistently at every stage of the procedure, including the paper chromatographic separation of fractions. Bioassays of norepinephrine with rat ascending colon were inconclusive since the concentrations, which according to the fluorimetric analysis were available, were on the borderline of the sensitivity of the test. Little biological activity was found in tests for epinephrine with rat uterus in spite of chemical evidence for its presence.