Rapid and sensitive liquid chromatography triple-quadrupole mass spectrometry methods for the analysis of per- and polyfluoroalkyl ether acids in water

Oral Presentation

Prepared by Z. Hopkins1, J. McCord2, M. Strynar2, H. Zhao3, J. Zweigenbaum4, T. Anumol4, D. Knappe1
1 - North Carolina State University, 2501 Stinson Drive, Raleigh, North Carolina, 27695, United States
2 - U.S. Environmental Protection Agency, , , United States
3 - Agilent Technologies, Inc, , , United States
4 - Agilent Technologies, Inc., , , United States


Contact Information: zrhopkin@ncsu.edu; 301-518-7697


ABSTRACT

Health risks associated with exposure to long-chain per- and polyfluoroalkyl substances (PFAS) has led to a shift towards the production and use of shorter-chain PFAS and fluorinated alternatives. Per- and polyfluoroalkyl ether acids (PFEA), in which one or more ether oxygen atoms are incorporated into the fluorinated carbon chain, represent one class of fluorinated alternatives. Occurrence of short-chain PFAS and PFEA in water supplies is a concern because conventional and many advanced water treatment processes are not effective for their removal. Our research aims to (1) develop rapid and sensitive direct injection and automated SPE methods for PFAS, including PFEA, and (2) investigate occurrence of PFAS in North Carolina water supplies.
An Agilent 1260 liquid chromatography Ultivo triple-quadrupole mass spectrometry system was used to develop a large volume (200-L) direct injection method that currently targets 7 perfluorocarboxylic acids, 5 perfluorosulfonic acids, 3 fluorotelomer sulfonates, 3 perfluorosulfonamindes, 13 per- and polyfluoroalkyl ether carboxylic acids, and 4 polyfluoroalkyl ether sulfonic acids. For quantification, an isotope dilution approach is used for PFAS for which mass-labeled internal standards (IS) are available. Other PFAS are quantified with IS that exhibit similar retention times and structures. During the 18-minute analysis, analytes are separated on a C-18 column (4.6x50mm, 3.5m) using an eluent flow rate of 0.7 mL/min. PFAS are analyzed in negative electrospray ionization mode. The ion source temperature impacted response factors of ether carboxylic acids and sulfonic acids. For example, the response factor for GenX at 350C was only 30% of that at 100C. Also, for GenX and another branched PFEA, the [M-COOH]- ion dominated over [M-H]-. Depending on the PFAS, method reporting limits were 5-10 ppt. Efforts are ongoing to reduce run time and enhance sensitivity by automated SPE for continued quantification of PFAS in NC drinking water sources, wastewater, and landfill leachate.