Development of a PFAS Metrology Program at NIST

Abstract

The National Institute of Standards and Technology (NIST) has a wide range of Standard Reference Materials (SRMs) values assigned for legacy organic pollutants and emerging contaminants of concern. The latter class of chemicals can be challenging to analytical laboratories due to limited availability of analytical standards and standard measurement methods. SRMs can serve as test materials for method development, instrument validation, and quality assurance/quality control (QA/QC) of chemical measurements. An emerging and unique class of organic contaminants, per- and polyfluoroalkyl substances (PFAS) present measurement challenges to the environmental analytical community that can affect the accuracy and precision of quantitative measurements. PFAS are of interest based on their ubiquity in the environment, and have been observed in consumer products, consumer byproducts (e.g., dust, wastewater, and landfill leachate), and environmental compartments including humans and biota. In addition, there is data indicating a subset of PFAS are toxic to humans. NIST first became aware of these analytical challenges in 2004 and began to build a program designed to support measurements for PFAS measurements. Through this program, NIST researchers have actively engaged with a range of stakeholders, including chemical manufacturers, analytical laboratories, regulatory and non-regulatory government agencies, and academic researchers. Currently, NIST has 15 reference materials (human serum, house dust, sludge, fish tissue, etc.) with reported mass fractions of PFAS; however, there are relevant gaps in the NIST library of reference materials. A major need is for reference materials with high concentrations of PFAS, including technical and commercial mixtures, PFAS-impacted animals and plants, and PFAS impacted soils/sediments. Working with partners, NIST has been expanding its catalogue of reference materials for PFAS measurements to better meet the needs of stakeholders. Examples include the recently added aqueous film-forming foam (AFFF) reference materials, a set of commercial mixtures, that have been measured for PFAS and are available to aid in quantitative and qualitative measurements of legacy and newly identified PFAS. In addition, several reference materials are in development and include: AFFF-impacted soil materials, meat materials from heavily contaminated areas, two plant materials from heavily contaminated areas, fish tissue, and a drinking water reference material. Through the use of interlaboratory comparisons, NIST has assisted laboratories in better understanding the performance of their PFAS measurements in a wide range of materials, from human biological tissues to abiotic environmental matrices to food materials. These studies have included legacy and emerging PFAS, adapting to the evolving needs of laboratories to measure new chemicals. In addition to reference materials, NIST researchers recognized the need of laboratories for reliable reference data and data tools to support their PFAS measurements. Through collaboration with other US agencies, NIST developed a novel data management system and data tools that allowed for the sharing and analysis of qualitative PFAS data. Together, these materials and efforts aim to support and underpin public health and safety related to PFAS.