Time-Resolved Spectroscopy for Selective Determination of Fluorescent Diuretics

Abstract

The applicability of phase-resolved fluorescence spectroscopy has been shown for the resolution of mixtures of two diuretics (furosemide and triamterene) with closely overlapping fluorescence profiles. Phase-resolved intensity spectra were used to estimate the steady-state fractional intensities using a method based on nulling the contribution of one component in the total spectra of the mixture. The only requirements for the analysis are the knowledge of the steady-state spectra of the individual components and the precise phase angle for the suppression of each component in the mixture. This is a simple and rapid method that substitutes previous separation techniques that have normally been used for these compounds. One of the advantages of this work is that the information provided by the whole spectrum of the sample is not required. The detection limits are 9 ng mL−1 for triamterene and 8.5 µg mL−1 for furosemide. This procedure allowed the resolution of a two-component mixture at µg mL−1 level, with a relative standard deviation less than 8% (n = 7) and recoveries of the original drugs between 88% and 117%.