Co-Fluorescence Enhancement System Based on Phenyl Salicylate and Lanthanum for the Determination of Terbium

A sensitive co-fluorescence enhancement system was developed for the fluorimetric determination of terbium. The fluorescence intensity of the chelates of Tb3+ with phenyl salicylate in a solution containing Triton X-100 and ethanol were greatly enhanced by the addition of excesses of La 3+ , Lu 3+ , Y 3+ and Gd 3+ . The enhanced fluorescence intensity of the terbium chelates was 33, 20, 11 and 13 fold, respectively. At pH=9.0 the fluorescence intensity of the Tb 3+ system with phenyl salicylate and La 3+ is a linear function of concentration of Tb 3+ in the range of 5.0 × 10 −8 - 3.0 × 10 −6 mol/L. The detection limit (signal-to-noise ratio = 3) is 3.0 × 10 −9 mol/L.