Addressing the growing challenge of ‘forever chemicals’ in water

So-called ‘forever chemicals’ comprise a broad and diverse class of nearly 10,000 synthetic substances, including per- and polyfluoroalkyl substances (PFASs) as well as other perfluorinated compounds (PFCs). These materials are defined by the exceptional stability of the carbon–fluorine bond, which confers resistance to thermal, chemical, and biological degradation. As a result, many PFASs persist in the environment, bioaccumulate in living organisms, and biomagnify through food chains. Long-chain compounds such as perfluorooctanoic acid (PFOA, also known as ‘C8’) and perfluorooctane sulfonic acid (PFOS) have been particularly well documented in this regard.

The global inventory of fluorinated chemicals continues to expand, yet toxicological and environmental data are available for only a limited subset of these compounds. This knowledge gap, combined with the structural diversity of PFASs, presents significant challenges for environmental monitoring and regulatory compliance. Individual PFASs often occur at trace levels, even in drinking water, and their quantification typically requires advanced analytical instrumentation, skilled operators, and complex validation procedures. Consequently, routine monitoring of a broad range of fluorinated substances can be both time-consuming and costly.

A substantial proportion of synthetic organofluorine compounds in water is captured by the parameter ‘adsorbable organic fluorine’ (AOF). Non-targeted determination of AOF using Metrohm’s combustion ion chromatography (CIC) offers a practical and robust alternative to highly targeted PFAS analyses. By converting organically bound fluorine into inorganic fluoride for quantification, CIC enables rapid screening without prior knowledge of individual compound identities.

In this context, AOF measurement serves as an efficient first-tier assessment tool, providing a comprehensive overview of the total burden of organic fluorinated substances in water samples. Elevated AOF concentrations can then trigger follow-up analyses using targeted methods to identify and quantify specific PFASs of concern. This tiered analytical strategy supports more efficient resource allocation while improving insight into the presence and distribution of persistent fluorinated chemicals in aquatic environments.

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