Simplified and Fast Analysis of Perand Polyfluoroalkyl Substances in Non-potable Waters

Importance of the topic

Per- and polyfluoroalkyl substances (PFASs) are environmental contaminants with high persistence and bioaccumulative potential. Trace-level detection of these compounds in water is critical for assessing human and ecological exposure, guiding remediation efforts, and meeting regulatory requirements for drinking and non-potable waters.

Study objectives and overview

This work presents a streamlined method for simultaneous screening, identification, and quantification of 28 PFAS analytes in non-potable water matrices. The approach follows the ASTM 7979 protocol with a uniform sample preparation and direct injection strategy, targeting reporting limits as low as 10 ng/L for most compounds.

Used instrumentation

• Agilent 1290 Infinity II UHPLC system with multisampler, binary pump, and multicolumn compartment
• Agilent 6470A triple quadrupole LC/MS system
• Agilent MassHunter workstation software for instrument control and data analysis

Methodology and instrumentation

Water samples (5 mL) are mixed 1:1 with methanol, acidified, filtered through 0.2 µm NY/GF filters, and injected (30 µL) onto a ZORBAX RRHD C18 column at 50 °C. A binary gradient of 0.1 % acetic acid in water and methanol runs over 18 minutes at 0.4 mL/min. Negative electrospray ionization with dynamic MRM acquires transitions for targets and isotopically labeled surrogates. External calibration (1/x weighting) spans 5–200 ng/L.

Main results and discussion

The method demonstrates high specificity through ion ratio checks and retention time consistency (≤2 % RT error). Calibration curves achieved R2 > 0.99, with residuals ≤30 %. Reporting limits were set at 10 ng/L (20 ng/L for PFDS and PFHpS). Recovery studies at 10, 20, and 160 ng/L showed mean accuracies between 70–130 % and RSDs ≤30 %. Application to unknown water samples confirmed surrogate recoveries within acceptance criteria and consistent quantitation of PFASs where present.

Benefits and practical applications

• Minimal sample preparation with direct injection reduces analysis time and potential losses
• Broad analyte coverage including sulfonates, carboxylic acids, fluorotelomer sulfonates, and emerging PFASs
• Low reporting limits suitable for environmental monitoring and regulatory compliance
• Compatibility with routine QC/QA workflows in environmental and industrial laboratories

Future trends and applications

Advances in instrumentation, such as the Agilent 6495 triple quadrupole, will further lower detection limits and improve throughput. Expansion of analyte panels to include novel PFAS precursors, integration with high-resolution MS for non-target screening, and automation of sample handling are expected to enhance environmental surveillance and risk assessment efforts.

Conclusion

The validated UHPLC-MS/MS method offers a fast, reliable, and sensitive approach for quantifying a comprehensive suite of PFASs in non-potable waters. It meets stringent performance criteria for specificity, linearity, accuracy, and precision, making it a valuable tool for environmental analysts and regulatory labs.

Reference

ASTM 7979; EPA draft method 8327