Automated Solid Phase Extraction of PFAS from Aqueous Samples

Importance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants of high regulatory concern due to their persistence, mobility, and potential health impacts. Reliable analysis of PFAS in water requires robust sample preparation workflows. Automation of solid phase extraction (SPE) reduces manual labor, improves reproducibility, and helps laboratories meet growing testing demands under methods such as US EPA Method 1633.

Objectives and Study Overview

This study evaluated five automated SPE protocols using Agilent dual-phase PFAS WAX/Carbon S cartridges to meet the quality control criteria of EPA Method 1633 for aqueous samples. The goal was to identify the cartridge configuration and extraction procedure that deliver optimal recovery, precision, and minimal outliers in reagent water and real environmental matrices.

Methodology and Instrumentation

Five extraction approaches were compared:

• Two-step SPE with single-phase WAX cartridges plus loose carbon sorbent
• One-step SPE using dual-phase layered cartridges (200 mg WAX/50 mg Carbon S)
• One-step SPE using dual-phase blended cartridges (200 mg WAX/50 mg or 10 mg Carbon S)

All protocols followed the automated SPE steps of EPA Method 1633 and were performed on an Agilent PromoChrom eight-channel extractor with inline filters and anticlogging frits. Extracts were analyzed by LC/MS/MS using an Agilent 1290 Infinity II HPLC (PFAS-free kit) coupled to a 6495C triple quadrupole mass spectrometer with Jet Stream ionization.

Main Results and Discussion

Extraction recoveries and precision were assessed via initial demonstration of capability (IDC) and initial precision and recovery (IPR) in reagent water at 40 ng/L mid-level spikes. The blended cartridge containing 200 mg WAX and 10 mg Carbon S exhibited the fewest outliers, highest mean recovery (~106%) and tight RSD (<15%). Method detection limits (MDLs) for 45 PFAS ranged from 0.05 to 0.38 ng/L, meeting or exceeding EPA validation data. Method blanks remained below half the LOQ for all analytes. In real water matrices (private wells, wastewater lagoon effluent, landfill well), target PFAS were quantified with acceptable accuracy and precision. Matrix spikes (MS/MSD) also passed recovery (60–140%) and precision (<20% RPD) criteria.

Benefits and Practical Applications

Automated SPE with optimized WAX/Carbon S cartridges streamlines PFAS sample preparation, cuts hands-on time, reduces variability, and supports high-throughput laboratories tasked with regulatory monitoring of drinking water, groundwater, and industrial effluents.

Future Trends and Opportunities

Continued development of sorbent chemistries and automation platforms will expand PFAS analysis to complex solid and biological matrices. Integration with online SPE-LC/MS workflows and further miniaturization may improve sensitivity, throughput, and sustainability of PFAS monitoring programs.

Conclusion

The Agilent dual-phase cartridge with 200 mg PFAS WAX and 10 mg Carbon S provides a validated, automated SPE solution for PFAS analysis in water that aligns with EPA Method 1633 QC metrics. Adoption of this approach enhances laboratory efficiency and data quality for routine environmental testing.

Reference

• Raynie DE. Trends in Sample Preparation, Part 1: Current State of the Field. LCGC Europe 2023;36(09):369–374.
• U.S. EPA Method 1633A: Analysis of PFAS in Aqueous, Solid, Biosolids, and Tissue by LC-MS/MS; EPA 820-R-24-007, 2024.
• Giardina M. Determination of PFAS in Drinking Water Using Agilent Bond Elut PFAS WAX SPE and LC/MS/MS. Agilent Tech. 2023.
• Giardina M. Determination of PFAS in Soils Using Carbon S SPE by LC/MS/MS. Agilent Tech. 2022.
• DOD/DOE Quality Systems Manual for Environmental Laboratories; Version 6, 2023.
• EPA. Definition and Procedure for the Determination of the MDL—Revision 2; CFR Part 136, App. B, 2025.