Sensitive determination of enoxacin by its enhancement effect on the fluorescence of terbium(III)–sodium dodecylbenzene sulfonate and its luminescence mechanism

The fluorescence system of enoxacin–Tb3+–sodium dodecylbenzene sulfonate (SDBS) was investigated in this paper. The experiments indicated that the fluorescence intensity of Tb3+–SDBS was greatly enhanced by enoxacin. Accordingly, a sensitive fluorimetric method for determining enoxacin was established. The fluorescence intensity was measured by a 1-cm quartz cell with an excitation wavelength of 290 nm and an emission wavelength of 545 nm. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of enoxacin in the range of 5.0×10−9 to 2.0×10−6 mol L−1, its correlation coefficient was 0.9992 and the detection limit (S/N=3) was 2.8×10−9 mol L−1. The presented method was used to determine enoxacin in real pharmaceutical samples. The luminescence mechanism was also discussed in detail. In the fluorescence system of enoxacin–Tb3+–SDBS, SDBS not only acted as the surfactant but also acted as the energy donor.