Detecting the elusive forever chemicals using combustion ion chromatography

Significance of the Topic

Per and polyfluorinated alkyl substances persist in the environment and bioaccumulate through food chains, posing serious risks to human health and ecosystems. Their resistance to water, oil and heat makes them difficult to remove with conventional methods. Targeted mass spectrometry detects only known PFAS molecules, leaving many precursors and unknowns unmonitored.

Objectives and Study Overview

This summary covers a Thermo Fisher Scientific webinar presenting combustion ion chromatography as a screening tool for extractable organic fluorine (EOF) and adsorbable organic halides (AOX) in environmental water samples. The aim was to evaluate CIC performance for PFAS prescreening and complement targeted LC MS MS workflows.

Methodology and Instrumentation

Sample preparation begins with automated adsorption of halogenated organics onto granular activated carbon. The loaded carbon is introduced into a high temperature combustion furnace to oxidize organic halogens into gaseous halides. These pass through a gas absorption unit and the resulting ionic solution is analyzed by ion chromatography using an isocratic 30 millimolar potassium hydroxide eluent. The system employed was a Thermo Fisher Scientific Dionex Integrion HPIC with an eluent generator, autosampler, combustion furnace and gas absorption module.

Main Results and Discussion

Recovery experiments in spiked wastewater demonstrated recoveries of 107–110 percent for fluoride, 90–108 percent for chloride and 103–114 percent for bromide at concentrations from 50 to 574 µg/L, with relative standard deviations under 5 percent. Measurements of perfluorobutanesulfonic acid and 4-fluorobenzoic acid in surface water, groundwater and wastewater matrices yielded recoveries between 85 and 127 percent. Chromatograms showed distinct peak resolution within ten minute runs. Automated eluent generation eliminated manual errors and software integration reduced sample cycle time by ten minutes per run.

Benefits and Practical Applications of the Method

• Automated prescreening of total organic fluorine and halides in water
• Enhanced sensitivity for trace level detection in parts per billion
• Reduced manual handling and operator error
• Cost effective complement to targeted MS screening
• Identification of samples for subsequent high resolution unknown screening

Future Trends and Potential Applications

As regulatory bodies expand PFAS monitoring requirements, integration of CIC can improve detection of unknown precursors. Coupling CIC prescreening with high resolution mass spectrometry will streamline discovery of new PFAS. Advances in software automation and eluent technology promise further throughput gains and simplified workflows.

Conclusion

Combustion ion chromatography provides a rapid, precise and automated method for determining adsorbable organic halides and fluorine in environmental waters. By complementing targeted LC MS MS, CIC uncovers previously undetected PFAS fractions and supports comprehensive water quality assessment.

Reference

1. National Institute of Environmental Health Sciences Perfluorinated Chemicals PFCs fact sheet 2012
2. United States Environmental Protection Agency Per and Polyfluoroalkyl Substances PFAS 2019
3. Agency for Toxic Substances and Disease Registry Overview of Perfluoroalkyl Substances and Interim Guidance for Clinicians 2019
4. Organization for Economic Co operation and Development Lists of PFOS PFAS PFOA PFCA and related compounds 2007
5. Organization for Economic Co operation and Development Toward a new comprehensive global database of PFASs 2018
6. Houtz EF Sutton R Park JS Sedlak M Poly and perfluoroalkyl substances in wastewater Water Res 2016 95 142 149
7. DAgostino LA Mabury SA PFAS associated with AFFF are widespread in Canadian surface waters Environ Sci Technol 2017 51 13603 13613