The TF of AFFF was determined by combustion ion chromatography (CIC; Metrohm). AFFF was diluted 500 times with Milli-Q water. Diluted AFFF (100 μL) was decomposed at 1050 °C in the combustion module (Analytik Jena), and fluorine carried by argon gas was trapped by a 920 absorber module as F -, which was quantified by IC (930 Compact IC Flex). The CIC measurement TF detection limit of 5 μg/L. Since no F -was detected in the AFFF, the TOF of AFFF samples equals their TF. Compared with other methods of TF estimation using targeted PFAS analysis (led to underreporting of TF ) and total oxidizable precursor assay (results subjected to digestion conditions ), CIC is the most suitable baseline for establishing a fluorine balance in this study.