An improved method for the fluorometric determination of tissue catecholamines

Catecholamines extracted from tissues are readily measured by fluorescence following trihydroxyindole derivatization. A complicating factor, however, has been the variably high background fluorescence levels obtained which adversely affect the precision of the assay. Employing EDTA is shown to reduce the high background fluorescence to a consistently low level, and to improve the accuracy of the trihydroxyindole method. It is suggested that high background fluorescence readings obtained by previous workers were due to metal ions extracted from tissue and carried over into the derivatization procedure.