Enhanced fluorescence of 3-tryptimino-1-phenyl-butan-1-one–Tb with 1,10-phenanthroline ternary system, and its analytical application

A new Schiff base ligand, 3-tryptimino-1-phenyl-butan-1-one (TPB), was synthesized. The fluorescence intensity of its terbium(III) complex was greatly enhanced by addition of 1,10-phenanthroline to an acetonitrile solution. Spectrofluorimetric determination of trace amounts of Tb³⁺ was performed based on this effect. The excitation and emission wavelengths are 293 and 546 nm, respectively. Under optimal conditions, the fluorescence intensities varied linearly with the concentration of Tb³⁺ in the range of 2.0 × 10⁻⁶ to 7.0 × 10⁻⁶ M with a detection limit of 2.4 × 10⁻⁹ M. Interference by some rare earth ions is described. This method was applied to the determination of trace amounts of terbium(III) in a high purity Y₂O₃ matrix. The mechanism of fluorescence enhancement was also studied.