Flow injection spectrofluorimetric determination of carvedilol mediated by micelles

A novel flow injection (FI)-spectrofluorimetric methodology for the determination of carvedilol in microheterogeneous medium has been developed. In the sodium dodecyl sulfate (SDS) surfactant medium, an additional fluorescence enhancement was produced by the electrolyte NaCl. A total enhancement of 3.1-fold in the native fluorescent response was achieved respect to aqueous medium. Using an excitation and emission wavelength of 286 and 341 nm, respectively, a good linear relationship was obtained in the range of 9x10(-8) to 1x10(-6) mol L(-1) with a detection limit of 3.63x10(-9) mol L(-1) (S/N=3). This method was applied to determine carvedilol in commercial pharmaceutical formulations. Good concordance was found between the nominal (6.25, 12.5 and 25.0 mg) and experimental values. The new methodology developed showed high selectivity respect to the common excipients used in pharmaceuticals. The sampling rate was 30 samples h(-1). From the fluorescent properties, binding constant for carvedilol-SDS determined was 3.2x10(2) L mol(-1).