Modified QuEChERS extraction coupled with LC-MS/MS for the determination of per- and polyfluoroalkyl substances in sediments.

A modified QuEChERS-based method combined with liquid chromatography-tandem mass spectrometry was developed for the determination of 25 per- and polyfluoroalkyl substances (PFAS) in sediment samples. The method achieved limits of quantification between 0.003 and 0.56 ng/g dry weight, inter-day precision ranging from 0.3 % to 16.2 %, and recoveries between 72 % and 117 %. The applicability of the procedure was confirmed through analysis of sediments collected from 18 sites along the Oder River. The total concentration of 14 detected PFAS ranged from 1.8 to 9.0 ng/g, indicating limited ecological risk. Short-chain perfluorocarboxylic acids, particularly C4, were the most abundant, while long-chain perfluorosulfonic acids, including C8, accounted for about one-third of the total PFAS burden. Emerging PFAS such as ADONA and GenX, which have been scarcely reported in European sediments to date, were detected, with higher concentrations observed in upstream sections. Elevated pH, TOC, and Na/K levels upstream of urban areas suggest anthropogenic impact prior to city inflow. Strong correlations among selected PFAS species point to shared sources, likely industrial discharge or degradation products. PFAS retention was strongly influenced by environmental parameters, with positive correlations to TOC and conductivity, and a negative correlation to pH. Partitioning analysis confirmed that long-chain PFAS exhibit greater affinity for sediments, supporting the role of sediments as long-term environmental sinks. The developed analytical procedure, evaluated as moderately green using modern tools for assessing the environmental sustainability of analytical methods, may serve as a useful approach for investigating the distribution and environmental behavior of PFAS in riverine systems.