LASER FLUOROMETRY OF FLUORESCEIN AND RIBOFLAVIN

The detection limits of fluorescein and riboflavin are determined to be 0.02 and 0.6 parts-per-trillion, respectively, with the use of a very sensitive fluorometric system (a nitrogen-laser-pumped dye laser and a pulse-gated photon counter). The dependences of the S/N ratio and the detection limit of the excitation and emission wavelengths are calculated and expressed in the figures for convenient determination of the optimal condition for ultratrace analysis. The results show that the Stokes shift of the sample molecule as well as the molecule's absorptivity, fluorescence quantum yield, fluorescence bandwidth influence the detection limit significantly. The present system incorporates an emission monochromator, this is especially useful for the analysis of a molecule with a small Stokes shift. © 1979, American Chemical Society. All rights reserved.