Fate Of Nitrofurans: Photochemistry, Transformation Products And Toxicity Evaluation In Surface Water Systems

Nitrofurans (NFs) consist a group of broad-spectrum antibiotic compounds provided as a basic dietary supplement in livestock husbandry as swine farms, beekeeping and aquaculture. Among nitrofurans furaltadone (FTD) is an antibiotic with a protective effect against bacterial and protozoan infections. Its application has been restricted in EU since 1993 followed by other NFs, as it exhibited toxicological effects in human. However, NFs are still supplied in many developing countries to date, because of high effectiveness and low cost. In this research, the photolytic behavior of NFs in aquatic environment as well as the photochemical transformation products were investigated using a solid phase extraction method coupled with UHPLC- LTQ/Orbitrap HRMS analysis. This study was conducted in distilled, lake, river and sea water under natural and artificial solar irradiation. The determined half-life times demonstrated that this process is the main degradation path of NFs in natural aquatic systems, compared to hydrolysis which presented negligible impact. Furthermore, the mechanism of NFs photodegradation in aqueous environment was exploited based on MS-MS data, indicating that hydrolysis, cleavage of carbon-nitrogen bond, and denitration etc are the dominant photochemical reactions. In addition, acute toxicity evaluation of NFs and photoproducts was performed, using Vibrio Fischeri as tested species. Finally, this study has as ultimate aim the investigation of the fate and impact of NFs and their transformation products, so in surface waters as in the related living organisms. Acknowledgements. The authors would like to thank the Unit of Environmental, Organic and Biochemical high-resolution analysis–Orbitrap-LC–MS of the University of Ioannina for providing access to the facilities.