When it comes to per- and polyfluoroalkyl substances (PFAS), traditional water sampling methods suffer from a high potential for cross-contamination and result in large volumes of investigation-derived waste (IDW), which is difficult and expensive to dispose of and can lead to stockpiled waste. The chemical properties of PFAS—relatively high solubility in water, surfactant properties and strongly variable molecular sizes—make legacy passive samplers unsuitable to PFAS.
Battelle has come up with a solution to this challenge with our PFAS Insight™ technology. This patent-pending passive sampler consists of a polymeric sorbent suitable for adsorbing neutral and ionic PFAS from a variety of aquatic environments. Laboratory testing conducted for PFAS compounds with carbon chain lengths from four to 12 showed strong preconcentration of the analytes and equilibration times of one to three weeks, depending on the analyte.
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Different geometries of the PFAS Insight sampler hardware have been designed to fit various applications, including groundwater monitoring wells and surface water/porewater sampling. We also are designing a sampler that can be used for sediment porewater sampling.
Field deployments conducted to date demonstrated a high degree of agreement between the PFAS Insight results and the results of grab water sampling analysis, with the majority of the surface water and more than half of the groundwater results agreeing
within five-fold, as bound by the dashed lines in Figure 3.
It should be noted that the two types of measurements are not equivalent because:
The passive sampler only measured the freely dissolved (unbound) fraction of PFAS, which may be different at each sampling location, whereas grab samples measure the total PFAS
The passive sampler results are time-integrated, whereas the grab water sampling results only represent the concentrations at one or two specific times
The purpose of this plot is not to provide a quantitative accuracy assessment, but rather to showcase the general agreement trend between the two methods. For a subset of groundwater wells, the passive sampler results were lower than those obtained from grab water sample analysis indicating that a big fraction of PFAS is not in its most bioavailable, freely dissolved form and/or that slow recharge of water into these wells resulted in incomplete equilibration of the passive samplers.
Comparison of PFAS Insight and grab water sampling analysis results. a) All results collected to date, b) All results except the monitoring wells where PFAS uptake by the passive sampler is suspected to be be significantly impacted by limited PFAS bioavailablity and/or slow well recharge.