Approaches towards sensitive and reliable determination of trifluoroacetic acid (TFA) from German grass- and farmland soils

In light of the emerging threat of environmental contamination from per- and polyfluoroalkyl substances (PFAS), there is a growing need for analytical techniques that can be applied to a range of environmental matrices, including water, air, plant, and soil samples. Trifluoroacetic acid (TFA) is a member of the PFAS class, representing the shortest perfluorinated carboxylic acid and is an emerging pollutant whose environmental levels are expected to increase in the future. Soil matrices represent the interface between plant and ecosystem uptake of TFA, but contamination is poorly understood, largely due to a lack of uniform TFA determination methods. This study compares six ways of determining TFA in soils and highlights their limitations. We present a validated sample preparation method with high recoveries (104 %), low LOD (0.015 ng/g) and LOQ (0.045 ng/g). This approach includes isotope dilution analysis with hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) detection. The method was applied to quantify the TFA content in 100 soil samples from grassland and farmland across Germany. The results indicate the ubiquity of TFA, accompanied by elevated contamination levels in certain locations. An analysis of variance revealed no correlation with collection site and designation purpose. However, a low correlation was observed with dry bulk density.