A Broad Mixture of Linear and Branched Perfluoroalkyl Substances (PFAS) in Hay: Results of an Interlaboratory Comparison

Poly- and perfluoroalkyl substances (PFAS) are a class of compounds with significant economic impact and various applications since the 1950s. Many PFAS accumulate in the environment and pose a threat to consumers through their transfer along the food chain, and are, therefore, classified as persistent organic pollutants. In this interlaboratory comparison, nine laboratories analyzed hay, grown on a highly contaminated field in Germany, for its PFAS content. In addition, three of these nine laboratories quantified branched PFAS isomers individually. The results show that PFAS are present in high concentrations (up to 148 μg/kg based on 88% dry weight; dw), with a considerable contribution (31%) of branched PFAS in the hay. The study also highlights challenges in the quantification of branched PFAS due to the lack of commercially available standard solutions. The performance of the participating laboratories was excellent, with 93% of the results falling in a <i>z</i>-score range within the acceptable limits of |±2|.