L. Rosenbergera, Y. Hövelmann,a, L. Wernerb, P. Kleinb, P. Appelbladc, R. Riggerd and M. Schulzb
a Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany
b Merck Life Science KGaA, Frankfurter Strasse 250, 64293 Darmstadt, German
c Merck Life Science AS, Drammensveien 123, 0277 Oslo, Norway
d Merck Chemicals and Life Science GmbH, Rechte Wienzeile 225, 1120 Wien, Austria
Email: patrik.appelblad@merckgroup.com
Per- and polyfluorinated alkyl substances (examples of PFAS chemical structures below) are synthetic compounds which have been widely used in various consumer and commercial applications over the past decades due to their versatile physical and chemical properties, e.g., in water repellent, firefighting foams, cookware, food packaging. As a result of chemical stability owing to the strong carbon-fluorine bond, the associated persistence and their toxicity, these compounds are however increasingly falling under scrutiny regarding contamination of water, soil, food and bioaccumulation in humans and animals.
Perfluorooctanoic acid PFOA and Perfluorooctanesulfonic acid (PFOS)
The United States Environmental Protection Agency (US EPA) and the European Union (EU) played key roles in issuing guidelines for PFAS testing regulations, which are essential to protect environmental and human health (e.g., EPA methods 533, 537.1 and 1633).1-3
The EPA Method 16331 is a laboratory-validated approach based on solid-phase extraction (SPE) and LC-MS/MS to analyze aqueous, solid, biosolid, and tissue samples for 40 PFAS across nine compound classes. The most recent version is referred as EPA 1633A and a key requirement for the successful application of the method is a high purity of the solvents and additives used for both the preparative and analytical stages of the analysis (e.g., for mobile phase, extraction reagents and calibration standard preparation). A presence of PFAS in these chemicals can lead to misleading results manifesting as false positives or overestimation of PFAS levels, and thus to undermining the validity of the analytical results and the drawn conclusions. Consequently, ensuring the purity of the solvents and additives is crucial for accurate and reliable PFAS analysis.
Three key solvents (acetonitrile, methanol, water) and four additives (ammonium acetate, acetic acid, formic acid, and ammonia/ammonium hydroxide) are used in these three methods. The presentation intends to discuss if and how analytical laboratory consumables meet international regulatory method requirements.
References
EPA Method 1633, Revision A, Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS. U.S. EPA. 2024.
Method 537.1 Determination of Selected Per- and Polyfluorinated Alkyl Substances in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS). U.S. Environmental Protection Agency, Washington, DC, 2020.
Method 533 Determination of Per- and Polyfluoroalkyl Substances in Drinking Water by Isotope Dilution Anion Exchange Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry. United States Environmental Protection Agency, Office of Water, December 2019.