Application of photochemical inhibition in flow injection systems: Determination of epinephrine and L-dopa

An automated procedure for the photochemical determination of epinephrine and L-dopa has been developed. It is based on the strong inhibition by these catecholamines on the photochemical reaction between phloxin and ethylenediaminetetraacetic. The proposed flow-injection method allows the fluorimetric determination of epinephrine in the range 1.9-26.4 mug/ml and of L-dopa in the range of 1.5-12.7 mug/ml, with a sampling frequency of 35 samples/hr. The method was applied successfully to the determination of body catecholamines in pharmaceutical preparations.