Determination of Norfloxacin by Sensitized Terbium Fluorescence in the Presence of Silver Nanoparticles and Surfactant Micelles

The effect of silver nanoparticles and surfactant micelles on their joint presence on the intensity of the sensitized fluorescence of the norfloxacin complex with the Tb³⁺ ion is studied. It is shown that the intensity of the intrinsic fluorescence of norfloxacin and its complex with Tb³⁺ ions in the presence of silver nanoparticles decreases slightly. It is found that, in the presence of dodecyl sulfate micelles, a modification of the surface of silver nanoparticles occurs, which is accompanied by a change in the ζ-potential of the nanoclusters. Additions of surfactant-modified silver nanoparticles to aqueous solutions of terbium chelate contribute to an 11-fold increase in the intensity of the sensitized fluorescence. An increase in the efficiency of intramolecular energy transfer in the Tb³⁺ complex with norfloxacin in the presence of silver nanoparticles and dodecyl sulfate micelles made it possible to propose a method for the fluorimetric determination of the antibiotic in natural water in the concentration range 2 × 10^–7−1 × 10^–5 M. The equation of the calibration graph is y = 1.0 × 10⁷x − 1.0, R² = 0.991, the limit of detection is 5 × 10^–8 M (3σ).