Analysis of PFAS in Wastewater Based on ISO21675 Using Triple Quadrupole LC/MS/MS

Significance of the Topic

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with widespread industrial and consumer applications due to their oil- and water-repellent properties.
Their strong carbon-fluorine bonds confer exceptional stability, raising concerns about bioaccumulation and toxicity.
Reliable, standardized analytical methods are essential to support regulatory monitoring and protect water quality.

Objectives and Study Overview

This work evaluates the performance of an LC-MS/MS method for simultaneous determination of 30 PFAS in wastewater following ISO 21675.
The study focuses on short-chain (C4) through long-chain (C16, C18) PFAS, comparing calibration, recovery, and repeatability in ultrapure water and industrial wastewater matrices.

Methodology and Instrumentation

Sample pretreatment adheres to ISO 21675:

• 100 mL water sample spiked with isotopically labeled internal standards (10 ng/mL).
• SPE using mixed-mode reversed-phase/anion-exchange (SHIMSEN Styra WAX) column with sequential neutral and ionic elution.
• Eluates dried under N2 at 40 °C, reconstituted to 1 mL in methanol (100× concentration).

Chromatographic separation on Nexera X3 HPLC:

• Shim-pack Scepter C18-120 (100×2.1 mm, 1.9 µm) with guard and PFAS delay column.
• Mobile phases: A) 2 mmol/L ammonium acetate in water; B) methanol.
• Gradient: 5% B to 50% in 2 min, to 100% from 19.0–23.0 min, return to 5% by 28.0 min.
• Flow: 0.3 mL/min (0–19 min), 0.6 mL/min (19.01–23 min), 0.3 mL/min (23.01–28 min).
• Column temperature 40 °C; injection volume 5 µL.

Mass spectrometry on LCMS-8060RX:

• ESI negative mode; interface 250 °C; interface voltage –1.0 kV; focus –2.0 kV.
• Nebulizing gas 3 L/min; drying gas 5 L/min; heating gas 15 L/min; DL temp. 200 °C; heat block 300 °C.

Calibration standards prepared from a 30-PFAS mixture (0.01–10 ng/mL, internal standard 1 ng/mL) measured in triplicate.

Used Instrumentation

• LCMS-8060RX triple quadrupole mass spectrometer
• Nexera X3 HPLC system
• Shim-pack Scepter C18-120 analytical and guard columns
• PFAS delay column (GL Science)

Main Results and Discussion

Calibration curves for all 30 PFAS showed excellent linearity (R>0.996) over the specified range, with peak area repeatability (n=3) <16% RSD.
Spike recovery in ultrapure water ranged 80–119% at 1 ng/L and 93–116% at 10 ng/L, meeting ISO requirements.
In industrial wastewater, recoveries at 1 ng/L were affected by background PFAS, yielding 59–170%, while at 10 ng/L recoveries improved to 81–116%.
Contamination control via delay and guard columns and PFAS-specific reagents proved critical for quantitation accuracy.

Benefits and Practical Applications

• Simultaneous quantification of 30 PFAS including long-chain species beyond EPA Method 1633.
• Low limits of quantification (0.01–0.05 ng/mL) suitable for regulatory water monitoring.
• Validated spike recoveries in ultrapure and complex wastewater matrices.
• Robust cleanup and contamination control enabling reliable routine analysis.

Future Trends and Opportunities

Advances may include automation of SPE workflows, integration with high-resolution MS and ion mobility for unknown PFAS screening, development of rapid on-site sensors, and AI-driven data processing for high-throughput environmental monitoring.
Emerging green extraction materials could further reduce solvent use and analysis time.

Conclusion

The LCMS-8060RX method following ISO 21675 provides accurate, sensitive, and reproducible analysis of 30 PFAS in wastewater.
It supports contaminated site assessment, regulatory compliance, and long-term environmental surveillance.

Reference

• ISO 21675:2019 Water quality — Determination of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in water — Method using solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS)