Estimation of total phenol content during photolysis of sulfamethoxazole in an aqueous medium
N.P. Bezlepkina1,2, E.N. Bocharnikova1,2, O.N. Tchaikovskaya1,2, O.K. Bazyl1, G.V. Mayer1
1National Research Tomsk State University, Tomsk, Russia
2Institute of Electrophysics of the Ural Division of the Russian Academy of Sciences, Ekaterinburg, Russia
Keywords: sulfamethoxazole, absorption spectrum, fluorescence, photolysis, phototransformation, photoreactor, total phenol content, photoproducts
Abstract
In natural and artificial water bodies, photolysis is the primary process that determines the transformation and fate of many pharmaceuticals. However, there is a lack of information on the degradation products of sulfonamide antibiotics and their toxicity. Phenols are potential transformation products of pharmaceutical contaminants and pose a threat to human health. This paper presents the results of an experimental study of the phototransformation of sulfamethoxazole in water. The irradiation experiments were carried out in a stationary photoreactor using KrCl (222 nm), XeBr (282 nm), and XeCl (308 nm) lamps and a bactericidal irradiator UVb-04 (180-275 nm) as sources of UV radiation. To determine the total phenol content in the photoproducts of sulfamethoxazole, a colorimetric method with Folin-Ciocalteu reagent was used. The changes observed in the absorption and fluorescence spectra after irradiation of aqueous sulfanilamide solutions are described in detail. The formation of three fluorescent photoproducts is shown, one of which is stable and accumulates in the solution regardless of the selected UV radiation source. The total phenol content increased after UV irradiation. It has been established that after 128 min of exposure to a KrCl excimer lamp, the total phenol content is 4 times higher than the initial value and amounts to 331.89 mg GAE/g. The results can be of interest for studying the degradation mechanism of sulfonamides, identifying toxic degradation products, and evaluating their antioxidant activity.
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