Practical Guidance on Selecting Analytical Methods for PFAS in Semiconductor Manufacturing Wastewater

The focus of this review is to provide an overview of the nomenclature, structure, and properties of perfluoroalkyl and polyfluoroalkyl substances (PFAS) that dictate the selection of analytical methods for analyzing PFAS in treated semiconductor wastewater. The review is organized by introducing the fundamental concepts of how structure dictates the physical-chemical properties of PFAS and how these properties determine the suitability and applicability of standardized analytical methods for individual PFAS as well as methods for total fluorine. Structures for PFAS measured in semiconductor wastewater or known to be in use by industry are given with tables intended as guidance for method selection. This review includes current guidance on sample collection, storage, and handling along with a comparison of U.S. Environmental Protection Agency and American Society for Testing and Materials analytical methods for target PFAS as well as methods for ultrashort PFAS. Methods are reviewed for volatile PFAS in wastewater as well as workflows for suspect and nontarget nonvolatile and volatile PFAS. Nonspecific methods for PFAS including the total oxidizable precursor assay, total fluorine analyses, and extractable and adsorbable organic fluorine assays are reviewed. Alternative detectors for total fluorine are reviewed along with nuclear magnetic resonance spectroscopy and sensors for online wastewater monitoring.