The purpose of this project is to field-validate the use of a portable electrochemical sensor technology for rapid assessment of per-and polyfluoroalkyl substances (PFAS) at Department of Defense (DoD) sites. PFAS are a group of anthropogenic chemicals that have demonstrated high persistence due to their physical and chemical properties. Among their many applications, their use in aqueous film-forming foams has resulted in groundwater and soil impacts at many sites. Comparatively low regulatory screening levels for PFAS have created a need for fast, reliable, and cost-effective measurement. The PFAS electrochemical sensor is an adaptable technology that will be integrated into a broad range of applications, such as initial characterization and remedy evaluation. This PFAS electrochemical sensor solves many challenges inherent to PFAS-impacted site evaluation and remediation efforts:

1. It provides a fast PFAS measurement, which is critical to evaluating performance of a corrective measure, especially when commercial analytical laboratories provide turnaround times of at least five business days;
2. It significantly decreases the cost per sample, allowing continuous and more thorough investigation of PFAS impacts with increased statistical significance;
3. It provides selectivity and sensitivity comparable to those obtained by laboratory methods, thereby preventing any data quality concerns.

The electrochemical sensor was developed collaboratively at the Pacific Northwest National Laboratory and New Jersey Institute of Technology. The flow through electrochemical sensor uses a nanoporous and capacitive electrode technology based on a nonplanar interdigitated microelectrode array (NP-IDμE). The NP-IDμE device consists of three layers: a top and bottom microelectrode (IDμE) and a middle layer of adsorptive probes (consisting of metalorganic framework, zeolites, covalent organic frameworks, or hierarchical porous carbons) to capture PFAS. The benefits of using these materials for PFAS capture are the separation of perfluoroalkyl chains from other organics and the tunable affinities toward PFAS functional groups to differentiate among them. The probe is designed as a mediator to transduce the chemical interaction signal to an electrical signal, which ultimately enables PFAS quantification.

As PFAS regulations become increasingly more stringent, fast, reliable, and cost-effective measurement becomes essential. This electrochemical sensor provides near real-time PFAS quantification with quality control commensurate to that of a commercial analytical laboratory. The benefit of near real-time, reliable PFAS measurement is multifaceted and includes screening of treatment system influent, mid-fluent, and effluent, screening of grab samples during site investigation, rapid profiling of suspected PFAS containing wastes, and compliance monitoring. With commercial PFAS analytical costs ranging from $300 to $500 per sample (depending on specifications), on-site PFAS quantification with this electrochemical sensor will significantly reduce analytical costs while also enabling greater data density to support the statistical significance of associated decision-making.