Per- and polyfluorinated alkyl substances (PFAS) have gained significant attention due to their persistence in the environment and potential bioaccumulative effects on ecosystems and human health. Specifically, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) have been widely detected in European rivers, leading to restrictions on their use. A 2015 study of the Danube River reported PFOA concentrations of 5-40 ng/L and PFOS concentrations of 5-30 ng/L. To evaluate the impact of these restrictions, this study measured the concentrations of PFOA and PFOS using UHPLC-QTOF systems, revealing a decreasing trend in their levels compared to earlier data.

Simultaneously, the growing demand for new organofluorine chemicals, particularly in lithium-ion battery production and the agrochemical and pharmaceutical industries, poses additional challenges. Municipal wastewater treatment plants are generally ineffective at removing these resistant fluorine-containing contaminants. To assess the fluorine content in riverine environments, the inorganic fluoride and total organofluorine concentrations in the dissolved water phase must be determined.

This study was focused on the analysis of PFAS compounds in water samples collected monthly from July to December 2023 at twelve sampling sites along the Hungarian section of the Danube River. Inorganic fluoride concentrations ranged from 28-106 µg/L, with a median of 45.3 µg/L, while total organofluorine concentrations ranged from 0.22-12.5 µg/L, with a median of 2.43 µg/L. The findings highlight the ongoing presence of fluorine-containing contaminants in the Danube River, despite regulatory efforts to reduce PFAS levels. These results underscore the need for continued monitoring and the development of more effective wastewater treatment technologies to address emerging environmental challenges.