Fluorimetric assay of flumequine using sensitized terbium fluorescence in organized media

Abstract

The effects of second ligands, micellar surfactant solutions, and microemulsions on the sensitized fluorescence signal from a chelate of Tb3+ with flumequine (FL) were studied. The presence of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline in a microemulsified medium of the “oil in water” type produced a six-fold increase in the sensitized fluorescence signal from the binary chelate of Tb3+ and FL. 1,10-Phenanthroline as a second ligand and micellar solutions of anionic surfactants increased emissions by a factor of 4.4 at pH 7.0. The latter system was used to develop a fluorimetric assay for flumequine operating over the concentration range 2.6 × 10−9to 0.26 × 10−6g/ml, R 2 = 0.997, with a detection limit of 1.3 × 10−9g/ml.