Differential fluorometry in catecholamine determination: a simplified method of calculation

A method for calculating the results of differential fluorometry in the determination of epinephrine and norepinephrine is des:ribed. A form which outlines the calcula-tions in steps is illustrated. This simplified method is applicable to differential flu-orometry and other procedures which involve solving two equations simultaneously. T0 SUBSTANCES with a marked difference in their excitatioim amid flu-orescence spectra can be readily measured independeimtly. However, whemi the spectra of the two substances overlap, one cannot be incas-ured imidependeimt of the other. Theim the principle of differeiitial flu-orometry is utilized. Measurements are made with two different sets of excitation and fluorescence wavelengths choseim to maximize the differ-ence 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 determina-tion. They indicated the equations involved and stated that the tw