Per- and polyfluoroalkyl substances (PFAS) are a set of emerging chemicals of concern resulting from the use of aqueous film-forming foams or similar products. PFAS are generally non-biodegradable and thus have long lifetimes in the environment. Measuring PFAS in surface and groundwater is important in understanding the transport and deciding upon remedial actions. A passive sampler for PFAS in aqueous systems will be developed and tested; a fast timetable is envisioned: the goal is to have a sampler fully developed and field tested within two years. Standard operating procedures (SOPs) will be developed in anticipation of future analysis by commercial and government laboratories. The passive sampler development leverages work conducted under SERDP project ER18-1300 where co-performers have developed organosilica adsorbents tailored to possess high capacity for PFAS regardless of chain length or charge state. As a result, work can begin immediately prototyping a passive sampler that is based on an organosilica absorbent placed in high density polyethylene (HDPE) housing. The project will progress through three phases: 1) passive sampler design selection, 2) performance validation in the laboratory and field, and 3) development of standardized methods that incorporate many of the protocols from US Environmental Protection Agency Method 537.1 and quality systems manual 5.2 to yield quality control and quality assurances using isotopic standards.

Passive samplers will use an organosilica adsorbent poly-quality assurance-Osorb that has both fluorophilic and ion-exchange functionality that allows high affinity for long-chain and short-chain PFAS. Fluoroalkyl groups are adsorbed to a hydrophobic expandable porous organosilica. The pores of the porous organosilica adsorbent contain a cationic polymer that binds anionic groups on perfluoro carboxylates and sulfonates, improving the affinity of short-chain compounds. Adsorbent will be placed in low cost 2.8×9.25 cm HDPE housings that can fit a wide range of monitoring wells, piezometers, and automated sampling systems, in addition to being able to be transported and analyzed in standard centrifuge tubes. An equilibrium-based sampler (preferred design) will be based on granular adsorbent placed between open mesh. An integrative design will be based on a single 1.0 cm diameter monolithic piece of adsorbent gel to allow a steady one-dimensional diffusion into the adsorbent disk. After a six-month benchmarking study, a final design will be selected. The selected design will then be evaluated and calibrated in a series of laboratory tests followed by field trials at up to three to five sites. Data obtained through these evaluations will be used to created SOPs for users and commercialized devices.

The development and demonstration of standardized procedures for field sampling of PFAS in environmental waters has been identified as a critical research priority. Passive samplers (available commercially through Aquanex) that can reach the market quickly offer a significant cost-savings to water analysis by simplifying sample collection, reducing shipping expenses, and reducing labor in the analysis, especially in the sample preparation steps. An additional benefit is the ability to leverage previous SERDP investments in developing Osorb media for PFAS adsorption. (Anticipated Project Completion - 2023)

Edmiston, P.L., E. Carter, K. Toth, R. Hershberger, N. Hill, P. Versluis, P. Hollinden, and C. Divine. 2023. Field Evaluation of the Sentinel™ Integrative Passive Sampler for the Measurement of Perfluoroalkyl and Polyfluoroalkyl Substances in Water Using a Modified Organosilica Adsorbent. Groundwater Monitoring and Remediation. doi.org/10.1111/gwmr.12574. (Open Source) 

Edmiston, P.L., N. Hill, R. Hershberger, H. Hartmann, E. Carter, and C. Divine. 2023. Laboratory Validation of an Integrative Passive Sampler for Per- and Polyfluoroalkyl Substances in Water. Environmental Science: Water Research & Technology, 9:1849-1861. doi.org/10.1039/D3EW00047H.

Hartmann, H., C. Hefner, E. Carter, D. Liles, C. Divine, and P. Edmiston. 2021. Passive Sampler Designed for PFAS Using Polymer-Modified Organosilica Adsorbent. AWWA Water Science, 3(4):e1237. doi.org/10.1002/aws2.1237.

Horst, J., C. Divine, J. Quinnan, J. Lang, E. Carter, T. Guillette, and V. Pulikkal. 2021. Where is the PFAS? Innovations in PFAS Detection and Characterization. Groundwater Monitoring and Remediation, 42(1):13-23. doi.org/10.1111/gwmr.12502.

Patent

Edmiston, P.L. and C. Divine. 2023. Passive Sampler. U.S. Patent 11650138B2.