Analysis of PFOA, PFHxS, and PFOS in Tap Water Using Triple Quadrupole LC/MS/MS

Significance of the Topic

The analysis of perfluorinated compounds such as PFOA, PFHxS, and PFOS in drinking water is critical due to their environmental persistence and potential health risks. Ensuring sensitive and reliable detection supports regulatory compliance and public health protection.

Objectives and Study Overview

This study aimed to develop and validate a triple quadrupole LC/MS/MS method on the LCMS-8050 for quantifying PFOA, PFHxS, and PFOS in tap water at concentrations down to 5 ng/L, representing less than one-tenth of Japanese water quality target values. A 1000-fold sample concentration approach was applied to meet stringent detection requirements.

Methodology and Instrumentation

Samples of 500 mL tap water were spiked with 13C-labeled internal standards (final 5 ng/L), then subjected to anion-exchange SPE using InertSep mini MA-2 cartridges. The eluate was concentrated under N2 to 0.5 mL and reconstituted with methanol.

• Liquid Chromatography: Shim-pack GIST C18-AQ HP column (150×2.1 mm, 3 µm) with 10 mmol/L ammonium acetate in water (A) and acetonitrile (B). Gradient from 25% to 100% B over 34 min, flow 0.2 mL/min, 40 °C, injection 5 µL.
• Mass Spectrometry: Shimadzu LCMS-8050, ESI negative mode, probe voltage –1 kV, gas flows (nebulizing 3 L/min, drying 5 L/min, heating 15 L/min), interface temp. 300 °C, MRM transitions set for each analyte and labeled standard.

Main Results and Discussion

Calibration curves for PFOA, PFHxS, and PFOS over 0.5–20 µg/L showed excellent linearity (r2>0.999). MRM chromatograms confirmed clear separation and detection at 5 ng/L. Spike-and-recovery tests in real tap water yielded recoveries of 95–111% with precision (%RSD) below 8%, demonstrating method accuracy and reproducibility.

Benefits and Practical Applications

The validated method enables routine monitoring of trace PFAS in drinking water at regulatory levels with high sensitivity and reliability. It supports water quality management, risk assessment, and compliance testing in environmental and analytical laboratories.

Future Trends and Opportunities

Advancements may include expansion to broader PFAS panels, adoption of ultra-high-pressure LC for faster runtimes, integration of on-line SPE, high-resolution MS for non-target screening, and AI-driven data analysis to enhance throughput and interpretative power.

Conclusion

The LCMS-8050 triple quadrupole approach, combined with targeted SPE concentration, delivers robust quantification of PFOA, PFHxS, and PFOS in tap water at sub-regulatory levels. The method meets stringent sensitivity, accuracy, and precision requirements for water quality monitoring.

References

1. Enactment of the Ministerial Ordinance on Water Quality Standards, Water Supply Division, Health Bureau, Japan, 2003 (amended 2020).