Differential Fluorometry in Catecholamine Determination: a Simplified Method of Calculation.

T0 SUBSTANCES with a marked difference in their excitatioim amid fluorescence spectra can be readily measured independeimtly. However, whemi the spectra of the two substances overlap, one cannot be incasured imidependeimt of the other. Theim the principle of differeiitial fluorometry is utilized. Measurements are made with two different sets of excitation and fluorescence wavelengths choseim to maximize the difference between the relaliL’e readings of the two substances while the absolute readings are kept relatively large. The concentration of each substaimce is then determined by solving two equations simultaneously. This principle may be utilized in analyzing mixtures of substances by measuring light absorption, radioactivity, aimd time like, as well as fluorescence. In the determinatiomm of epinephrilme and mmorepinephrine, both Price and Price (3) and Cohen aimd Goldenberg (2) independently suggested the utilization of slight differemmces in fluorescent properties of the indoles formed from these compounds for their differential determination. They indicated the equations involved and stated that the two