Assessing reliable measurements of total organic fluorine in food packaging materials

Per- and polyfluoroalkyl substances (PFAS) are a family of more than 15.000 substances, some of which are considered persistent environmental contaminants. Certain PFAS were commonly used in food contact materials (FCMs) to increase technical performance. Some non-polymeric PFAS species have been found to migrate into food and contribute to human and environmental exposure. Regulatory frameworks, such as the EU Packaging and Packaging Waste Regulation (PPWR) and Danish Executive Order No. 681 from 2020, are increasingly focusing on total fluorine (TF) and total organic fluorine (TOF) thresholds as proxies to control PFAS presence in packaging. However, current analytical methods face limitations in accurately quantifying TOF, particularly in complex matrices containing both organic and inorganic fluorine, generating false results. This study presents a robust method for indirect TOF determination in solid matrices, combining combustion ion chromatography (CIC) with an optimised pre-combustion step at 525 °C for 2 h. The method was validated using a diverse set of fluorinated compounds, including polymeric and non-polymeric organic fluorine, and tested on mineral fillers used in paper manufacturing. Compared to other pre-treatment methods for indirect TOF determination, aqueous extraction used to remove inorganic fluorine often overestimates TOF, likely because of its limited ability to fully extract inorganic fluorides. The proposed method minimises false positives and enhances the reliability of TOF quantification, supporting regulatory compliance and environmental monitoring. These findings underscore the importance of accurate TOF assessment in FCMs and highlight the need for harmonised analytical approaches to better evaluate organic fluorine contamination in consumer products, and their environmental implications.