Method Development and Validation of Per- and Polyfluoroalkyl Substances in Foods from FDA’s Total Diet Study Program

Abstract

Human exposure to per- and polyfluoroalkyl substances (PFAS) through the US diet has not been well-characterized. Highly consumed foods are routinely monitored through FDA’s Total Diet Study program. Portions of these samples were used to develop and validate a method for PFAS in a wide variety of foods. The extraction of 16 PFAS was performed using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and analyzed by liquid chromatography/mass spectrometry. Method optimizations are described including investigations into the QuEChERS sorbents, matrix effects, and solid-phase extraction (SPE) cartridges. The use of a custom push-through SPE cartridge showed promising results as a rapid cleanup option for food samples. Challenges in ion confirmation are discussed, and the use of enhanced product ion (EPI) full-scan MS/MS spectra is presented as a potential option for verifying false positives. The validated method was then used for the analysis of 179 total diet study samples, and positive detects for perfluorooctanesulfonic acid (PFOS) were found in two fish and one meat sample.

Extraction and Matrix Cleanup Method for Analyzing Novel Per- and Polyfluoroalkyl Ether Acids and Other Per- and Polyfluoroalkyl Substances in Fruits and Vegetables

“…Despite the different definitions of MQLs, the MQLs obtained in this study are comparable to those of previous studies (Table S1 of the Supporting Information). ,,− For example, the GenX MQLs in this study ranged from 0.038 to 0.01 ng/g depending upon the matrix, while the FDA-modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method reported GenX MQLs ranging from 0.01 to 0.083 ng/g. For PFOA and PFOS, MQLs were <0.05 ng/g in all matrices in this study, while MQLs between 0.007 and 0.090 ng/g were achieved in different matrices with the FDA-modified QuEChERS method (Table S1 of the Supporting Information).…”

“…There is a lack of a harmonized definition of MQLs in environmental and biological samples, making interlaboratory comparisons difficult. We summarized four types of PFAS MQLs that have been discussed in the literature (Table S10 of the Supporting Information): (1) instrumental detection limits (IDLs) of analytes in pure solvents, , (2) IDLs and procedure blanks (solvent blank), ,,,− (3) IDLs and matrix blanks, or (4) IDLs and the lowest quantifiable concentration in matrix-spiked samples. ,,, The last method considers interferences in the matrix and is supported by the U.S. EPA . However, it requires a matrix-matched calibration curve, which is time-intensive when many matrices, such as the 10 types of produce evaluated here, are involved.…”

“…14−16 Most human exposure studies have focused on legacy PFAS, such as PFOS and PFOA, and data on the occurrence of novel PFAS, such as PFEAs, in food are scarce. 17,18 PFEAs are a subclass of PFAS with one or more ether oxygen in the fluorocarbon backbone; 19 they are produced as alternatives to legacy substances or generated as byproducts during fluorochemical production. 20 For example, hexafluoropropylene oxide dimer acid and its ammonium salt (commonly known as GenX chemicals) were introduced as a PFOA alternative in fluoropolymer manufacturing.…”

“…Several U.S. states established regulatory limits for additional PFAS not addressed by federal guidelines and/or set lower limits. − In the early 2000s, production and use of long-chain perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) were phased out in some regions around the globe, and fluorochemical production transitioned to short-chain PFCAs and PFSAs as well as other subclasses, such as perfluoroalkyl ether acids (PFEAs). The environmental and human health impacts of many novel PFAS are poorly understood. − Most human exposure studies have focused on legacy PFAS, such as PFOS and PFOA, and data on the occurrence of novel PFAS, such as PFEAs, in food are scarce. , …”

“…A robust extraction method is needed to quantify PFEAs and other poorly understood PFAS in food. Most current food extraction methods focus on PFCAs and PFSAs. ,− Even for methods that include some novel PFAS, like GenX, ,, the number of targeted PFEAs was limited, and other PFAS subgroups, such as fluorotelomer carboxylic acids (FTCAs), were not included (Table S1 of the Supporting Information). Furthermore, some studies relied on acetonitrile as an extraction solvent.…”