Total organic fluorine to assess per- and polyfluoroalkyl substances (PFAS) in food contact materials: a call for harmonised methodologies

The widespread use of per- and polyfluoroalkyl substances (PFAS) presents health and/or environmental challenges due to their persistence. To address these concerns, regulatory bans on various applications, including food contact materials (FCMs), have intensified in recent years, with limits specifically addressing total organic fluorine (TOF) to account at least for both non-polymeric and polymeric PFAS while excluding inorganic fluorine contributions. This study aimed to conduct an interlaboratory comparison involving eleven laboratories to assess the consistency of TOF measurements across two types of FCMs: a polyolefin film and a paper-based material. The laboratories were not informed that they participated in this investigation to make sure the analysis was performed following their routine analysis. The findings revealed substantial discrepancies in TOF results, especially for the paper-based material, while total fluorine (TF) measurements were more consistent for both samples. A thorough comparison of the five different standards and in-house methodologies employed by the laboratories indicated the pre-treatment step may be the primary factor influencing TOF values, in contrast to the combustion and fluoride detection steps. The lack of standardised procedures for TOF measurements in FCMs raises concerns about the reliability of results, especially in the presence of inorganic fluorine, which could be mistakenly interpreted as indicative of PFAS. These results underscore the urgent need for harmonised analytical methods to improve the accuracy and comparability of total organic fluorine assessments across laboratories.