Factors Contributing to Lower Surrogate Recoveries in PFAS Analysis Based on ISO 21675 and the River Survey of PFAS in Osaka City, Japan

In 2020, a guideline value of 50 ng L-1 for the total content of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in public waters was established by the Water Pollution Prevention Act of Japan. However, concerns about emergent and alternative per- and poly-fluoroalkyl substances (PFAS) have been raised in recent years due to their global use and disposal. In this study, 30 legacy and emergent PFAS in water were analyzed according to the ISO 21675 guidelines. When river water was analyzed, surrogate recoveries for some PFAS decreased. This decrease was attributed to ionization suppression during liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. In the spike and recovery tests, the PFAS recovery rates of ultrapure and river water were 88-122% and 66-141%, respectively, confirming the robustness of analytical accuracy. Twenty PFAS compounds were detected, with ΣPFAS30 concentrations ranging from 24 to 11,000 ng L-1 in the rivers of Osaka City, Japan. The maximum PFAS concentration was observed in Kanzaki River, and with perfluoro-n-hexanoic acid (PFHxA) accounting for 98% of ΣPFAS30, reaching a concentration of 10,800 ng L-1. The sampling site was affected by the activities of a fluororesin manufacturer. The measurement of 6:2 fluorotelomer sulfonic acid (6:2 FTSA) was detected at the sampling site affected by sewage treatment plant effluent, while hexafluoropropylene oxide dimer acid (HFPO-DA) was detected at all sampling sites. The comparison of the PFOS and PFOA concentrations in this study area with those from a previous 2007 survey revealed average decreases of one-tenth and one-seventh, respectively. These findings improve our understanding of PFAS distribution in water and highlight the importance of ongoing monitoring efforts in mitigating potential environmental risks.