Total oxidizable precursors assay for PFAS in human serum. (December 2022)

• Record Type: Journal Article
• Authors: Cioni, Lara; Nikiforov, Vladimir; Coêlho, Ana Carolina M.F.; Sandanger, Torkjel M.; Herzke, Dorte
• Is Part Of: Environment international. Volume 170(2023)
• Publication Date: 2022-12
• Subjects: TOP assay -- PFAS -- Precursors -- Human exposure -- Method development; AMAP Arctic Monitoring and Assessment Programme -- FOSA Perfluorooctane sulfonamide -- FTCA Fluorotelomer carboxylic acid -- FTOH Fluorotelomer alcohol -- FTS Fluorotelomer sulfonate -- FTUCA Fluorotelomer unsaturated carboxylic acid -- HCl Hydrochloric acid -- ISTD Internal standard -- K2S2O8 Potassium persulfate -- LOD Limit of detection -- LOQ Limit of quantification -- MeOH Methanol -- MTBE Tert-butyl methyl ether -- Na2S2O8 Sodium persulfate -- NaOH Sodium hydroxide -- NH4OAc Ammonium acetate -- PFAS Per- and polyfluoroalkyl substances -- PFCA Perfluoroalkyl carboxylic acids -- PFECA Perfluoroalkyl ether carboxylic acids -- PFSA Perfluoroalkyl sulfonic acids -- PFAA Perfluoroalkyl acids -- RSTD Recovery standard -- TOP Total Oxidizable Precursors; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2022.107656
• Languages: English
• ISSNs: 0160-4120

Abstract

Graphical abstract: Abstract: Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals including over 4700 substances. As a limited number of PFAS is routinely analyzed in human serum, complementary analytical methods are required to characterize the overlooked fraction. A promising tool is the total oxidizable precursors (TOP) assay to look for precursors by oxidation to perfluoroalkyl acids (PFAA). The TOP assay was originally developed for large volumes of water and had to be adapted for 250 μL of human serum. Optimization of the method was performed on serum samples spiked with model precursors. Oxidative conditions similar to previous TOP assay methods were not sufficient for complete oxidation of model precursors. Prolonged heating time (24 h) and higher oxidant amount (95 mg of Na2 S2 O8 per 225 μL of serum) were needed for complete conversion of the model precursors and accomplishing PFAA yields of 35–100 %. As some precursors are not fully converted to PFAA, the TOP assay can only provide semi-quantitative estimates of oxidizable precursors in human serum. However, the TOP assay can be used to give indications about the identity of unknown precursors by evaluating the oxidation products, including perfluoroalkyl sulfonic acids (PFSA) and perfluoroalkyl ether carboxylic acids (PFECA). The optimized TOP assay for human serum opens the possibility for high-throughput screening of human serum for undetected PFAA precursors.