Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic chemicals that have been manufactured for over 60 years and are widely used in diverse products, including fire-fighting foams, insecticides, stain-resistant fabric, and food contact paper and packaging. Due to the chemical and thermal stability of the C-F bond, PFASs have been frequently detected in different environmental compartments, aquatic organisms, and humans. Investigation of PFAS partitioning between water and various solid-phases is critical to evaluate risk. In this respect, samples usually require filtration before extraction and/or analysis. However, few studies have rigorously examined PFAS retention on various filter media, which can introduce significant analytical bias to measured concentrations. In this study, we investigated the retention of chemically-diverse PFASs (e.g., perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, fluorotelomer sulfonates, and perfluorooctane sulfonamides) on seven filter types (i.e., glass fiber, nylon, polyethersulfone, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride/ difluoride, and surfactant-free cellulose acetate). PFAS retention was examined using flow-controlled syringe pump systems and separate batch equilibrium experiments. The impacts of filter pore size (e.g., 0.20 and 0.45 μm), initial PFAS concentration (e.g., 1 and 100 μg/L), filtration flow rate (e.g., 0.5 and 1.0 mL/min), and sample matrix (e.g., deionized water and surface water) were carefully examined. Select PFASs, especially the perfluoroalkyl sulfonates, were partially or totally retained during the filtration process for some or all of the tested filter types. For example, 100 μg/L perfluorooctanesulfonate in 50 mL of solution was completely retained on nylon filters. The loss of some PFASs during filtration results in under-quantitation of their actual concentrations since surrogates and/or internal standards are typically spiked after filtration. The results of this study highlight the need to account for analyte loss during filtration when measuring PFASs in environmental samples.

Retention of per- and polyfluoroalkyl substances during filtration: Implications for proper sample pretreatment

2019 Spring National Meeting

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