Can Large-Volume Filtration Using Capsule Filters Reduce the Sorption Loss of Per- and Polyfluoroalkyl Substances (PFAS)?

Sorption loss of per- and polyfluoroalkyl substances (PFAS) during filtration has been a known issue, impeding studies of PFAS partitioning between dissolved and particulate phases in water. In this study, we demonstrated the use of large-volume filtration through capsule filters to reduce PFAS sorption loss. Membrane materials of polypropylene (PP), poly(ether sulfone) (PES), nylon, polyvinylidene difluoride (PVDF), polytetrafluoroethylene (PTFE), and glass fiber (GF) were selected to evaluate the sorption loss of 40 PFAS at environmentally relevant concentrations in pure water and seawater. The overall performance of the tested membranes ranks as follows: GF > PES ≈ PP > PTFE > PVDF > nylon. GF membranes exhibited the lowest sorption loss (<10% for most PFAS), and no isomeric composition was altered during filtration. Compared to pure water, seawater increased the sorption loss of ultralong-chain PFAS and precursors, likely due to high salinity and pH, which cause salting-out and cation-bridging effects and alter PFAS speciation. Our results highlight that large-volume filtration using GF membranes effectively minimizes the sorption loss of many legacy and emerging PFAS to achieve accurate dissolved-phase PFAS concentrations, enhancing current sampling methods for PFAS phase-partitioning studies, especially for PFAS in estuarine and coastal waters.