Monitoring PFASs in water sources

Importance of the Topic

The growing concern over per- and polyfluorinated alkyl substances (PFASs) stems from their extreme environmental persistence and potential health risks. These compounds are widely used in industrial applications such as firefighting foams and protective coatings, but they accumulate in ecosystems and biomagnify through the food chain. Reliable and efficient screening methods for PFAS contamination in water sources are essential for environmental monitoring and regulatory compliance.

Objectives and Study Overview

This study evaluates a non-targeted sum parameter, adsorbable organically bound fluorine (AOF), as a rapid screening tool for PFASs in water. Based on DIN 38409-59, the approach combines automated adsorption of organofluorines on activated carbon with pyrohydrolytic combustion and ion chromatography (CIC) to quantify total bound fluorine in various water samples.

Methodology

Sample Preparation

• Surface water and two wastewater samples were adjusted to neutral pH by adding sodium nitrate to prevent inorganic fluoride adsorption.
• Activated carbon cartridges captured organofluorine species from 100 mL samples at 3 mL/min, followed by a rinse with dilute sodium nitrate.
• Cartridges were transferred to ceramic boats for analysis.

Analytical Procedure

• Combustion at 1 050 °C volatilized halogens and sulfur; the resulting gases were absorbed in the 920 Absorber Module.
• Aqueous extracts were injected into the ion chromatograph using precise Dosinos, separating fluoride on a Metrosep A Supp 5 column.
• Automated eluent production and intelligent partial loop injection provided a calibration range of 0.01–0.5 mg/L from a single standard.

Used Instrumentation

• 930 Combustion IC PP system with pyrohydrolysis and IC detection
• 920 Absorber Module for gas dissolution and liquid handling
• 930 Compact IC Flex oven with sequential suppression and built-in degasser
• Metrohm Metrosep A Supp 5 Guard/4.0 and 250/4.0 separation columns
• MMS 5000 Autosampler for solid sample introduction

Main Results and Discussion

Replicate analyses (n=4) yielded AOF concentrations ranging from 6.52 µg/L in surface water to 9.70 µg/L in one wastewater sample. Relative standard deviations were between 3.6% and 5.3%, demonstrating excellent repeatability. The method blank was determined at 1.1 µg/L, and results were corrected accordingly. Automated sample preparation and analysis ensured consistent data quality and high throughput.

Benefits and Practical Applications

• Rapid, non-targeted screening of a broad range of PFASs without specialized mass spectrometry.
• Fully automated workflow from sample loading to data acquisition supports routine monitoring in environmental and industrial laboratories.
• Combined analysis of organofluorine and other halogen sum parameters is possible using the same system setup.

Future Trends and Opportunities

Advances in sum parameter methods may include expanded detection of adsorbable organically bound chlorine, bromine, and iodine, enabling comprehensive halogen profiling. Integration with high-resolution detection techniques could further characterize PFAS species. Continuous automation and miniaturization will drive higher throughput and lower detection limits, supporting real-time environmental surveillance.

Conclusion

The CIC-based AOF determination according to DIN 38409-59 offers a fast, reliable, and automated screening approach for PFAS contamination in water. It complements targeted LC-MS/MS analyses by providing sum parameter data that guide more detailed investigations and regulatory decisions.

References

1. Gehrenkemper L, Simon F, Roesch P, et al. Determination of Organically Bound Fluorine Sum Parameters in River Water Samples. Anal Bioanal Chem. 2021;413(1):103–115.
2. Willach S, Brauch H-J, Lange FT. Contribution of Selected Per- and Polyfluoroalkyl Substances to the Adsorbable Organically Bound Fluorine in German Rivers. Chemosphere. 2016;145:342–350.
3. Lanciki A. Adsorbable Organic Fluorine (AOF) – a Sum Parameter for Non-Targeted Screening of PFASs in Waters. WP-078EN; Metrohm AG; 2021.
4. Shoemaker J, Tettenhorst D. Method 537.1: Determination of Selected PFASs in Drinking Water by LC/MS/MS. EPA; 2018.