Trace Level Determination of PFOS, PFOA and HBCD in Drinking Water by Direct Aqueous Injection on the Agilent 6495 LC/MS/MS

Significance of the Topic

Perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and hexabromocyclododecane (HBCD) are persistent organic pollutants of global concern due to their environmental persistence, bioaccumulation and potential human health risks. Monitoring these compounds at trace concentrations in drinking water is critical to ensure compliance with regulatory limits and to safeguard public health.

Objective and Study Overview

The study aimed to develop a robust, high-throughput analytical method for the routine quantification of PFOS, PFOA and HBCD in drinking water. The approach employs direct aqueous injection on an Agilent 6495 triple quadrupole LC/MS/MS system, minimizing sample preparation steps while maintaining low detection limits and high precision.

Methodology and Instrumentation

Sample preparation consists solely of direct aqueous injection, eliminating conventional extraction or cleanup. A trapping column placed between the mixing point and analytical column reduces background contamination from perfluorinated chemicals and brominated flame retardants.

• Agilent 1290 HPLC system
• Agilent 6495 LC/MS/MS with Jet Stream interface
• PFOS/PFOA: Eclipse Plus C18 column (2.1×100 mm, 1.8 µm)
• HBCD: Poroshell 120 Phenyl-Hexyl column (2.1×100 mm, 2.7 µm)
• Trapping column: Poroshell 120 EC-C18 (3×50 mm, 2.7 µm)
• Injection volume: 20 µL; flow rate: 0.4 mL/min; run time: 9.6 min

Results and Discussion

Calibration curves for PFOS, PFOA and HBCD isomers were linear over 0.25–50 ng/L with correlation coefficients above 0.995. At 1 ng/L, chromatographic separation from background interferences was achieved. Precision studies yielded relative standard deviations below 6% for PFOS/PFOA at 0.5–1 ng/L and below 7% for HBCD isomers at 1–2.5 ng/L. The trapping column effectively reduced system-borne contamination, ensuring low background levels.

Benefits and Practical Applications

This method offers:

• Minimal sample handling and reduced analysis time
• Lower risk of contamination from consumables
• High reproducibility due to elimination of extraction variability
• Trace-level detection suitable for regulatory compliance

Future Trends and Potential Use

Direct aqueous injection combined with high-efficiency LC/MS/MS is likely to expand into other water matrices and environmental samples. Advances in miniaturization, automation and improved trapping materials may further lower detection limits. Growing regulatory demands for emerging contaminants will drive method adaptation and standardization.

Conclusion

A sensitive, streamlined LC/MS/MS method using direct aqueous injection and a trapping column on the Agilent 6495 system has been demonstrated for trace-level PFOS, PFOA and HBCD in drinking water. The approach achieves excellent linearity, precision and low background, supporting routine monitoring workflows.

References

1. Directive 2006/122/EC of the European Parliament and Council on restrictions for perfluorooctane sulfonates.
2. Risk Assessment Report on Hexabromocyclododecane, SCHER, May 2008.
3. Stockholm Convention on Persistent Organic Pollutants, COP6 report, UNEP, 2013.
4. Commission Regulation (EU) No 143/2011 amending Annex XIV to REACH Regulation (EC) 1907/2006.