Determination of Per- and Polyfluoroalkyl Substances in Water by Direct Injection of Matrix-Modified Centrifuge Supernatant and Liquid Chromatography/Tandem Mass Spectrometry with Isotope Dilution
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- Document: Report (5.35 MB pdf) , HTML , XML
- Data Release: USGS data release - Concentrations of per- and polyfluoroalkyl substances (PFAS) from validation experiments and custom sample analysis by U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) Laboratory Code 9660, December 2020 to March 2022
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Abstract
A direct-injection liquid chromatography/tandem mass spectrometry method was developed to determine 34 per- and polyfluoroalkyl substances (PFAS), including selected branched isomers, in centrifuge supernatant of matrix-modified (amended with approximately 50 percent methanol) water samples. The method has been validated in reagent water, surface water, groundwater, and wastewater effluent. Other water types (for example, drinking water, untreated wastewater, and landfill leachate) have been analyzed by the method but not systematically validated. Recovery of isotope-dilution standards, added to each sample, may be used to assess method performance in nonvalidated matrices on a sample-by-sample basis.
Using this method, PFAS concentrations were determined in the range of 2–2,000 nanograms per liter in water samples. This range can be extended by diluting concentrated samples. At circumneutral pH, most compounds are present in the environment in their ionized form, and data are reported as such (for example, perfluorooctanoic acid is referred to as “perfluorooctanoate” [PFOA], perfluorooctane sulfonic acid is referred to as “perfluorooctane sulfonate” [PFOS]).
Sample preparation procedures were designed without the use of filtration and with minimum sample handling steps to mitigate procedural losses of target compounds due to sorption to surfaces. Further, isotope-dilution quantification allowed for the correction of bias that may result from procedural losses, matrix-induced signal suppression or enhancement, and other factors.
Validation experiments to characterize bias and variability, method detection level, and holding time were done in four distinct water matrices—reagent water, surface water, treated wastewater effluent, and groundwater—at multiple concentration levels. Mean PFAS recoveries met data quality objectives of bias and variability studies in all four validation matrices except for two compounds with low and variable recovery in the reagent water matrix only. Isotope-dilution standards, treated as surrogate compounds, were analyzed in more than 1,500 customer-submitted environmental samples with aggregate recovery of 102.5±6.5 percent (mean±standard deviation). Maximum holding times for all target compounds in the four validation matrices were 28 days for refrigerated samples and 90 days for frozen samples.
Suggested Citation
Gray, J.L., Kanagy, L.K., Kanagy, C.J., and Anderson, C.A., 2025, Determination of per- and polyfluoroalkyl substances in water by direct injection of matrix-modified centrifuge supernatant and liquid chromatography/tandem mass spectrometry with isotope dilution: U.S. Geological Survey Techniques and Methods, book 5, chap. B13, 121 p., https://doi.org/10.3133/tm5B13.
ISSN: 2328-7055 (online)
Table of Contents
- Acknowledgments
- Abstract
- Introduction
- Background
- Summary of Method
- Analysis by Liquid Chromatography/Tandem Mass Spectrometry—Setup and Data Acquisition
- Quantification, Calculation, and Reporting of Results
- Results and Discussion of Method Validation Experiments
- Bias and Variability from Matrix-Spike Recovery Experiments
- Stability Study and Determination of Maximum Holding Time
- Performance of Batch Quality-Control Samples During Custom Analysis Period
- Problematic Compounds
- Summary and Conclusions
- References Cited
- Appendix 1. Supplemental Figures
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Determination of per- and polyfluoroalkyl substances in water by direct injection of matrix-modified centrifuge supernatant and liquid chromatography/tandem mass spectrometry with isotope dilution |
| Series title | Techniques and Methods |
| Series number | 5-B13 |
| DOI | 10.3133/tm5B13 |
| Publication Date | July 09, 2025 |
| Year Published | 2025 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston VA |
| Contributing office(s) | WMA - Laboratory & Analytical Services Division |
| Description | Report: xii, 121 p.; Data Release |
| Online Only (Y/N) | Y |