The co-luminescence effect of a europium (III)-lanthanum (III)-gatifloxacin-sodium dodecylbenzene sulfonate system and its application for the determination of trace amount of europium (III)

A novel co-luminescence system based on the formation of a complex between europium (III) (Eu3+) and gatifloxacin (GFLX) in sodium dodecylbenzene sulfonate (SDBS) micelle solution containing lanthanum (III) (La3+) has been developed for the determination of Eu3+. The experimental results show that the complex formed by Eu3+ and GFLX here can emit the characteristic luminescence of Eu3+. With the addition of La3+, the luminescence intensity of the system was enhanced about 7-fold compared with that without La3+. Under the optimal conditions, the luminescence intensity exhibits an excellent linear relationship with Eu3+ concentration in the range of 1.0×10−10-5.0×10−8 mol L−1. The correlation coefficient (r) is 0.9998, and the detection limit (3σ) is 7.0×10−14 mol L−1. A test method with satisfactory accuracy based on this system was applied to determine trace amounts of Eu3+ in rare earth samples. In addition, the detailed luminescence mechanism of this system was investigated by analyzing the ultraviolet absorption spectra, surface tension, fluorescence polarization, quantum yield, and the number of water molecules in the first coordination sphere of the Eu3+ complex.