Analysis of >50 Legacy and Emerging PFAS in Water Using the Agilent 6495B Triple Quadrupole LC/MS

Significance of the Topic

The increasing global prevalence, persistence, and potential toxicity of per- and polyfluoroalkyl substances (PFAS) in aquatic environments demand sensitive and reliable analytical methods. Accurate quantitation at trace levels is essential for tracking environmental fate, evaluating ecological risks, and supporting regulatory decisions.

Objectives and Study Overview

This study presents a single, robust LC/MS/MS method for the simultaneous quantitation of 53 legacy and emerging PFAS across 14 compound classes in water matrices. The approach combines isotope dilution with an Agilent 1290 Infinity II LC and Agilent 6495B triple quadrupole mass spectrometer to deliver high sensitivity and throughput.

Methodology and Instrumentation

• Sample Preparation: A 250 mL water sample is filtered, spiked with 21 isotopically labeled standards, and extracted via weak anion exchange solid-phase extraction.
• Chromatography: Separation on an Agilent ZORBAX Eclipse Plus RRHD C18 column (2.1 × 50 mm, 1.8 µm) with ammonium acetate buffer and methanol gradient (10 % to 100 % B) at 400 µL/min over 15 minutes.
• Mass Spectrometry: Agilent 6495B QqQ in negative electrospray ionization (ESI) with multiple reaction monitoring (MRM). Gas temperature 250 °C, nebulizer 25 psi, sheath gas 375 °C; optimized transitions and collision energies set via MassHunter Optimizer.

Main Results and Discussion

• Instrument detection limits (IDLs) ranged from 2.5 to 469 fg on-column; 22 compounds achieved IDLs below 10 fg.
• Method detection limits (MDLs) spanned 0.28–18 ng/L, and quantification limits (MQLs) 0.35–26 ng/L, with 46 PFAS quantifiable below 5 ng/L.
• Extraction recoveries for 49 compounds fell between 70 % and 130 % (RSD < 20 %); a few analytes deviated due to surrogate mismatches.
• Matrix spike experiments in wastewater demonstrated 80 %–120 % recoveries for 47 PFAS, confirming minimal matrix effects.
• Application to influent and effluent samples from three wastewater treatment plants detected 21 PFAS at concentrations up to 56 ng/L, revealing distinct PFAS profiles by treatment facility.

Benefits and Practical Applications

• A unified method enables comprehensive monitoring of a wide range of PFAS in environmental waters.
• Reduced run time (~15 min vs. ~27 min) and enhanced sensitivity facilitate high-throughput analysis.
• Reliable trace-level detection supports regulatory compliance, risk assessment, and remediation studies.

Future Trends and Applications

• Extension to additional PFAS classes, including isomer-specific analyses and novel emerging compounds.
• Integration with high-resolution mass spectrometry for suspect and non-target screening workflows.
• Automation and miniaturization of sample preparation for on-site or near-real-time PFAS monitoring.

Conclusion

The described SPE-LC/MS/MS protocol using an Agilent 6495B triple quadrupole system delivers sensitive, accurate, and efficient quantitation of 53 PFAS in water. Its high throughput and robust performance make it well suited for environmental surveillance and regulatory applications.

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