Abstract E uler U. S. v . and F. L ishajko . Improved technique for the fluorimetric estimation of catecholamines. By the addition of small amounts of ethylene diamine (EDA) to the alkali‐ascorbic acid mixture used in the trihydroxyindole (THI) method the discoloration of reaction mixture and instability of fluorescence can be prevented, allowing blanks to maintain their fluorescence values for several hours. The lutines obtained from adrenaline and noradrenaline standards and from alumina eluates are stable over a period of at least one hour. Optimal fluorescence values are obtained when the volume of alkali‐ascorbic‐acid ‐ EDA exceeds the volume of the sample by 1 ml. A proportional increase in fluorescence is observed with sample volumes up to 3 ml. The technique used for estimation of catecholamines in urine and organ extracts is described. The importance of the acidity for the release of catecholamines from conjugates in urine at room temperature is emphasized.
Euler et al. (1961) studied this question.