Sorption–Fluorimetric Determination of Enrofloxacin Using Fibers Formed by Electrospinning

Abstract

The work is devoted to the development of a method for the sorption–fluorometric determination of enrofloxacin in aqueous solutions using sensitized fluorescence on the surface of a nanofiber formed by electrospinning. Enrofloxacin is a broad-spectrum antibacterial agent; as an inhibitor of bacterial DNA gyrase, it is widely used in livestock, poultry, and fisheries, and as a growth promoter and in food additives. However, the wide and often unjustified use of antibacterial substances is a reason for exceeding the permissible values of their residual quantities in the food raw materials and food products and in natural and waste waters, which necessitates monitoring of their contents. The effect of the nature of polymer fibers, the concentration of terbium ions, the acidity of the medium, and the nature of the surfactant on the recovery of enrofloxacin and the fluorescence intensity of the analytical system was studied. Polyacrylonitrile fiber formed from a 13% solution in dimethylformamide by electrospinning was selected as a sorbent. It was shown that, in the presence of terbium ions, the recovery of fluoroquinolone increased fivefold and reached 91%. The increase in this indicator is associated with the enhancement of electrostatic and hydrophobic interactions of the chelate with the sorbent, as well as with the possible implementation of the coordination binding of terbium ions with the nitrile group of polyacrylonitrile. The addition of micelles of cationic, nonionic, and anionic surfactants has virtually no effect on the recovery of enrofloxacin. The optimal sorption time was 90 min. It was shown that multilayer adsorption structures could form on the fiber surface as the enrofloxacin concentration was increased. The proposed sorption–fluorometric method for the determination of enrofloxacin is characterized by a low limit of detection of 1 × 10^–7 M and a fairly wide analytical range of 4 × 10^–7−5 × 10^–4 M. The method was tested on natural waters, and its accuracy was controlled by the added–found method.