ИСТИНА

The antibiotic ciprofloxacin is widely used in medicine, agriculture and veterinary. Accidental releases of antibiotics into wastewater, soil, or natural water reservoirs are common occurrences that fundamentally affect natural ecosystems. That is why it is extremely important to develop methods for determining the concentration of antibiotics in water and soil, taking into account the presence of organic substances of natural origin (humic substances) in them. This work is aimed to develop an optical method for determining the concentration of ciprofloxacin in the presence of humic substances in aqueous medium. Ciprofloxacin exhibits fluorescence with an emission maximum at 435 nm and an excitation maximum at 275 nm, however, its emission band in natural water or soil overlaps with the fluorescence of humic substances. To determine the concentration of ciprofloxacin in the presence of humic substances, we propose to use synchronous fluorescence spectra that selectively highlight the fluorescence of the antibiotic. It was found that ciprofloxacin is most clearly detected at a difference in excitation and emission wavelengths of 160 nm. Quantitative determination of ciprofloxacin is carried out by the wavelength-integrated intensity of the spectrum, obtained as the difference between the synchronous fluorescence spectrum of the soil extract with and without ciprofloxacin. In a model experiment with 6 types of soil contaminated with ciprofloxacin, the antibiotic concentrations in soil extracts were measured with the help of developed technique.