A highly luminescent complexes of Eu(III) and Tb(III) with norfloxacin and gatifloxacin doped in sol–gel matrix: A comparable approach of using silica doped Tb(III) and Eu(III) as optical sensor

Highly luminescent complexes of Eu and Tb ions with norfloxacin (NFLX) and gatifloxacin (GFLX) were prepared in sol–gel matrix. The red and green emissions of Eu and Tb ions were obtained by the energy transfer from the triplet state of (NFLX) and (GFLX) to the excited emitting states (5D0 and 5D4) of Eu and Tb, respectively. The intensity of the electric field emission bands (5D0→7F2, 617 nm and 5D4→7F5, 545 nm) of Eu and Tb ions were proportional to the concentration of (NFLX at pH 6.0) and (GFLX at pH 3.5) in acetonitrile with excitation wavelengths (λex) (340 and 395) and (370 and 350 nm) for Eu and Tb ions, respectively. The monitored luminescence intensity of the system showed a good linear relationship with the concentration of NFLX within a range of 5×10−9–5.8×10−6 and 5×10−8–1.0×10−6 mol L−1 with a correlation coefficient of 0.990, and for GFLX within a range of 2.4×10−9–3.2×10−5 and 5×10−8–8.0×10−6 mol L−1 with a correlation coefficient of 0.995. The detection limit (LOD) was determined as 3.0×10−9 and 1.0×10−8 mol L−1 for NFLX and 1.6×10−10 and 2.0×10−8mol L−1 for GFLX. The limit of quantification (LOQ) is 9×10−9 and 3.0×10−8 and 4.8×10−10 and 6.0×10−8 in case of Eu and Tb, respectively.