Analysis of PFAS and further VOC from fluoropolymer-coated cookware by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS).

Abstract

Per- and polyfluoroalkyl substances (PFAS) are used in the production of PTFE based coatings for cookware. In this study, emission of PFAS and further volatile organic compounds (VOC) from kitchenware articles were investigated. First, method development for thermal extraction of baking trays, frying pans and baking mats at 250 °C was done by testing three different extraction devices. A thermal desorption oven showed the best blank and highest recoveries of PFAS analytes (70-101% for 12 perfluorocarboxylic acids (PFCAs), 2 fluorotelomer alcohls (FTOHs), 3 per- and polyfluoroether carboxylic acids (PFECAs), 1 polyfluoroether (PFE)). Second, 18 cookware samples, a PTFE micro powder and 2 lab made coating strips have been investigated. No PFAS were detected in 12 samples (limits of detection: 1-13 ng/dm²). PFCAs (C5-C23) were detected in a baking tray in amounts up to 34 ng/dm². A baking mat contained 3 ng/dm² PFOA. FTOHs were not detected in the samples. A PFECA (bC7O2) and its hydride (bC6O2H PFE) were detected in one coating intended for use in frying pans. The hydrides of the PFECA mixture, b(C3O1)_nC3 PFECA (Krytox 157FSH), were detected in five baking trays. The PFAS target analytes were not detectable in the five investigated frying pans. Analysing further VOC in the emissions of coatings, 175 compounds could be identified, including alkanes, alkenes, aromatic substances, esters, aldehydes, ketones, ethers, alcohols, carboxylic acids, siloxanes and sulphur, nitrogen, as well as chlorine containing compounds (< 10 µg/dm²). The identified substances cannot be connected to the basic coating polymer of the kitchenware articles, which were PTFE and PES. All samples have undergone a threefold thermal extraction. No substances could be detected in the second and third consecutive extraction, which means that a removal and no new formation of the investigated PFAS as well as the further VOC at 250 °C has occurred.