Perfluorinated Alkyl Substances (PFAS) in Drinking Water: Extraction Using the PS2 Cartridge in Accordance with EPA 537.1

Importance of PFAS Analysis in Drinking Water

Perfluorinated alkyl substances (PFAS) are persistent environmental contaminants with potential health risks. Monitoring PFAS in drinking water is critical for regulatory compliance and public safety. The US EPA Method 537.1 sets strict criteria for extraction, precision, and accuracy to ensure reliable detection at trace levels.

Study Objectives and Overview

This study aimed to demonstrate that the Sep-Pak PS2 Cartridge provides equivalent solid-phase extraction (SPE) performance to the styrene divinylbenzene substrate required by EPA Method 537.1. Drinking water samples, both tap and bottled, were processed and analyzed to verify recovery, precision, and incurred PFAS levels.

Methodology and Instrumentation

The workflow followed EPA 537.1 specifications:

• Sample Preparation and Extraction: Drinking water fortification and SPE using Sep-Pak PS2 Cartridges (p/n: WAT200610).
• Chromatography: ACQUITY UPLC I-Class PLUS System for compound separation.
• Detection: Xevo TQ-S micro Tandem Quadrupole Mass Spectrometer for targeted PFAS quantitation.

Main Results and Discussion

• Recovery Performance: All 18 regulated PFAS exhibited recoveries within 80–125% across fortification levels (0.5, 1.0, 4.0, and 16.0 ng/L), meeting the 70–130% guideline.
• Precision: Six replicate extractions in tap and bottled water yielded %RSD values below 10% for most compounds (all below 16%), satisfying the <20% requirement.
• Incurred PFAS Levels: Bottled water contained PFHxA, PFHpA, and PFOA at 0.02–0.22 ng/L. Tap water showed seven PFAS (PFHxA, PFHpA, PFOA, PFNA, PFBS, PFHxS, PFOS) at 0.39–1.99 ng/L.

Benefits and Practical Applications

Implementation of the Sep-Pak PS2 Cartridge:

• Meets regulatory extraction chemistry with no method modifications.
• Delivers consistent accuracy and precision for routine PFAS monitoring.
• Simplifies laboratory workflows by using a direct SPE equivalent.

Future Trends and Opportunities

Advancements may include:

• Expanded target lists covering emerging PFAS chemistries.
• Automation of SPE for higher throughput and reduced variability.
• Application to complex matrices beyond drinking water, such as wastewater or food samples.

Conclusion

The Sep-Pak PS2 Cartridge has been validated as an equivalent SPE phase for EPA Method 537.1, providing robust, accurate, and precise extraction of PFAS from drinking water. This approach supports regulatory compliance and enhances laboratory efficiency.