The total phenolic content in an aqueous solution of chloramphenicol under exposure to UV and e-beam irradiation

Absorption, fluorescence and cathodoluminescence methods were used to study the transformation of chloramphenicol in water. The Folin-Ciocalteu reagent method was used to determine the total phenolic content (TPC) after the transformation of the antibiotic. New experimental data were obtained on the TPC reduction after the transformation of chloramphenicol in water under the action of UV sources (KrCl, XeBr, XeCl, Xe₂ excilamps and a UVb-04 bactericidal irradiator) and an e-beam. Using HPLC-MS, 5 final products of the antibiotic transformation were found after 1600 pulses of e-beam exposure. After UV irradiation, accumulation of two final photoproducts fluorescing in the region of 350 nm and 430-450 nm was recorded. It was found that the conversion of chloramphenicol in water under the action of an e-beam (when the pulse duration of 2 ns, numbers of pulses from 50 to 3200, an average electron energy of 170 keV, a current density of 130 A/cm², a pulse energy density of 44.2 mJ/cm², and a pulse repetition rate of 1 Hz) was 98.2 %. TPCs in an aqueous solution of chloramphenicol were 23.33 ± 1.63 and 20.19 ± 1.41 mg GAE/g after irradiation with a Xe₂ and the е-beam, respectively. The TPC in aqueous chloramphenicol solution remained stable high at 163.86 ± 11.47 mg GAE/g after exposure to KrCl excilamp irradiation. According to the absorption and fluorescence spectra, it was found that the products of chloramphenicol transformation in water under exposure to e-beam irradiation were minimal, compared to UV irradiation. The obtained data are important for further understanding of the pathways of chloramphenicol transformation affected by the artificial UV and e-beam radiation.