Targeted PFAS Analysis in Industrial Wastewater Using the Agilent 6475 Triple Quadrupole LC/MS System

Importance of Topic

Per- and polyfluoroalkyl substances (PFAS) are widely used industrial chemicals that resist degradation and accumulate in water bodies. Their persistence and potential health risks have led to stringent regulations worldwide. Accurate quantification of PFAS in industrial wastewater is critical for environmental monitoring, regulatory compliance, and risk assessment.

Aims and Study Overview

This study presents a targeted workflow for the analysis of 71 native and 37 isotopically labeled PFAS in industrial effluent. It extends beyond US EPA Method 1633 by evaluating an expanded list of compounds. The primary objectives were to develop a reliable sample preparation protocol, optimize LC-MS/MS acquisition using a triple quadrupole system, and verify method performance metrics.

Methodology

Sample preparation followed EPA 1633 guidelines with modifications:

• Ten milliliters of raw wastewater were fortified with extracted internal standards (EIS).
• pH adjustment to 6–7, followed by Solid Phase Extraction (SPE) on Agilent Bond Elut PFAS WAX cartridges.
• Eluate cleanup via a Carbon S cartridge and evaporation under nitrogen to achieve a 20× preconcentration.
• Non-extracted internal standards (NIS) were spiked prior to analysis to monitor recovery.

Chromatographic separation employed an Agilent 1290 Infinity II LC with a ZORBAX RRHD Eclipse Plus C18 column and a gradient of ammonium acetate in water and methanol at 0.4 mL/min. Detection was achieved on an Agilent 6475 triple quadrupole MS using negative electrospray ionization and Multiple Reaction Monitoring (MRM) transitions from the Agilent PFAS MRM database.

Applied Instrumentation

• Agilent 1290 Infinity II LC system with polyfluorinated compound-free HPLC flow path.
• ZORBAX RRHD Eclipse Plus C18 column (2.1 × 100 mm, 1.8 µm).
• Agilent 6475 triple quadrupole mass spectrometer with AJS ESI source.
• Agilent MassHunter LC/MS Acquisition and Quantitative Analysis software (v12.0).

Main Results and Discussion

Initial calibration across seven levels showed linearity for all target PFAS (RSE ≤ 20%). Method detection limits (LOQs) were at or below 5 ng/L for 93% of analytes, in line with or better than EPA 1633 pooled ranges. Accuracy and precision were assessed with low-spike (0.0125–0.125 µg/kg) and high-spike (0.25–2.5 µg/kg) QC samples:

• Recoveries for 70 of 71 compounds in low-spike samples ranged from 50 to 130%.
• High-spike recoveries for all targets met the 70–130% criterion with RSD ≤ 20%.
• Real wastewater analysis detected over ten PFAS above LOQ, including legacy and emerging substances such as PFOA, PFOS, HFPO-DA and shorter‐chain acids.

These results confirm the high sensitivity, selectivity, and reproducibility of the workflow.

Benefits and Practical Applications

The validated method provides an end-to-end solution for industrial PFAS monitoring. Key advantages include:

• Broad target coverage exceeding current regulatory lists.
• Low detection limits suitable for wastewater surveillance.
• Robust SPE cleanup ensuring high recoveries in complex matrices.
• Compliance with international guidelines (EPA 1633, REACH, EU POPs).

Future Trends and Opportunities

Emerging directions in PFAS analysis may include non-target screening with high-resolution MS, automation of SPE workflows, on-site portable instrumentation for rapid screening, and expansion of target lists to capture novel PFAS. Integration of data analytics and machine learning could further enhance detection capabilities and interpret complex environmental datasets.

Conclusion

The optimized SPE-LC/MS/MS method on the Agilent 1290 Infinity II and 6475 triple quadrupole system achieves sensitive, accurate, and precise quantitation of an extensive PFAS panel in industrial wastewater. It meets or exceeds regulatory performance criteria and offers a reliable tool for environmental laboratories and industrial compliance teams.

References

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