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Understanding PFAS and Combustion-Ion Chromatography

By 06.18.2025

Per- and polyfluoroalkyl substances (PFAS) comprise more than 14,000 synthetic fluorinated compounds. These substances, known for their persistence and bioaccumulation, have been widely used in various industrial and consumer products since the 1940s. However, their environmental and health impacts have raised significant concerns. PFAS compounds, such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), have been linked to potential reproductive health issues. The U.S. Environmental Protection Agency (EPA) has defined methods for analyzing PFAS, including US EPA Method 1621, which prescribes the use of combustion-ion chromatography (C-IC) for the detection of adsorbable organic fluorine (AOF) in water.

What is AOF?

Adsorbable organic fluorine (AOF) refers to the total amount of organic compounds containing fluorine that can be adsorbed onto activated carbon or other adsorbents during water treatment processes and within analytical procedures. High levels of AOF can indicate the presence of harmful perfluorinated and polyfluorinated substances (PFAS), which are persistent in the environment and potentially harmful to human health and ecosystems. Monitoring AOF helps assess contamination levels and the effectiveness of purification techniques.

What is EPA method 1621 for?

U.S. EPA method 1621 is a laboratory procedure designed to measure the concentration of adsorbable organic fluorine (AOF) in water and wastewater samples. It uses activated carbon to adsorb organic fluorine compounds, followed by combustion and analysis of the resulting gases to quantify the fluorine content. This method is useful for detecting and quantifying the presence of perfluorinated and polyfluorinated compounds, which are often difficult to analyze directly due to their extensive structural diversity.

This C-IC analysis of AOF determines a measure of the total organofluorine content in a sample, serving as a broad screening tool for these substances.

Why use combustion-ion chromatography?

As part of EPA method 1621, C-IC offers a robust solution for PFAS analysis. The Thermo Scientific application note, Enhanced screening of PFAS compounds in wastewater: Implementing U.S. EPA Method 1621 with improved combustion-ion chromatography, demonstrates that the Thermo Scientific Cindion Combustion Ion Chromatography System can reduce contamination and enhance sensitivity of AOF determination, demonstrating significant improvements over previous methods.

  • Accurate and sensitive detection: Achieve precise measurement of PFAS compounds with high sensitivity, ensuring even trace amounts are detected.
  • Improved efficiency and throughput: Process multiple samples simultaneously with a semi-automatic adsorption module, optimizing laboratory workflows and saving time.
  • Minimal contamination: Reduce baseline contamination to enhance the reliability and accuracy of results.
  • Efficient combustion and data management: Utilize optimized combustion techniques and streamlined data management with integrated software for better operational efficiency.
  • Approved method compliance: Ensure adherence to EPA Method 1621 for non-targeted PFAS determination.

This advanced technique is crucial for accurately measuring PFAS in environmental samples, ensuring better protection of public health and the environment.

To learn more about C-IC and its applications in PFAS analysis, visit our Combustion-Ion Chromatography Learning Center.

Visit us on LinkedIn: #PFAS #EPAMethod1621 #CIC

Terri Christison

Terri Christison is Application Staff Scientist, Ion Chromatography/Sample Preparation, Thermo Fisher Scientific