A sensitive and specific fluorimetric method for the determination of noradrenalin and adrenalin in human plasma

A sensitive and specific fluorimetric method which allows measurement of plasma noradrenalin and adrenalin concentrations even at physiological levels is described. A two-step Chromatographie separation on alumina and Amberlite CG-50 (Na + form) is employed, perchloric and boric acids being used for elution. Fluorophores of increased fluorescence intensity and stability are obtained by using a dimercaptopropanol-formaldehyde solution as antioxidant. The smallest amount of noradrenalin or adrenalin which would double blank values is about 50 picograms. When this procedure is applied to 10 ml venous plasma of normal subjects at rest, fluorimetric readings of the samples, 4–10 times blank values are obtained and excitation spectra show the typical morphology of noradrenalin and adrenalin fluorophores. Fluorimetric discrimination allows sufficiently accurate differential estimation of mixtures of the two amines in 1:25 proportion. Normal values in peripheral venous plasma for noradrenalin were 174 ± 24 ng/l and for adrenalin 66 ± 13 ng/l (mean ± S.D.).