Novel semi-automated method for the analysis of per- and polyfluoroalkyl substances (PFAS) in soil samples

Význam tématu

Per and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with widespread use and strong potential for bioaccumulation. Their mobility in soil and water and links to adverse human health effects have prompted regulatory agencies to develop sensitive analytical protocols. Reliable quantification of PFAS in soils at parts-per-trillion levels is critical for monitoring contamination and guiding remediation efforts.

Cíle a přehled studie

This study aimed to adapt the Thermo Scientific EXTREVA ASE accelerated solvent extractor and Dionex AutoTrace 280 PFAS system to meet US EPA Method 1633A requirements for soil analysis. The objectives were to automate extraction and cleanup steps, reduce manual labor and PFAS background contamination, and validate method performance in terms of sensitivity, linearity, recoveries, detection limits, and carry-over.

Použitá metodika a instrumentace

Gas assisted dynamic accelerated solvent extraction (GA-dASE) was performed on the EXTREVA ASE system using stainless steel cells, 80:20 methanol:acetonitrile solvent, 60 C temperature, and high pressure. Semi-automated solid phase extraction cleanup was integrated into the ASE workflow by passing diluted extracts through graphitized carbon black/weak anion exchange cartridges on the AutoTrace 280 PFAS system. Final analysis employed Vanquish Flex Binary UHPLC coupled to a TSQ Altis triple quadrupole mass spectrometer configured for negative electrospray SRM detection.
Instrumental configuration and key parameters

• EXTREVA ASE with PFAS upgrade kit and PEEK tubing
• Dionex AutoTrace 280 PFAS for combined GCB/WAX SPE cleanup
• Vanquish Flex Binary UHPLC with delay column and Acclaim RSLC 120 C18 analytical column
• TSQ Altis triple quadrupole mass spectrometer with HESI source, negative mode, S/N ≥ 10 at 0.05 ng/g

Hlavní výsledky a diskuse

Instrument background PFAS levels measured by blank ASE extractions were all below the US EPA Method 1633A MDL of 0.06 ng/g. Laboratory MDLs determined by spike and blank based protocols matched or improved on EPA MDLs across 40 PFAS analytes. Recoveries in spiked clean loamy soil (n=7) averaged 80–120 for 37 of 40 analytes, with relative standard deviations below 20. Surrogate recoveries fell within 55–110 and RSD ≤15. Certified reference material analysis yielded 73–98 recoveries for most PFAS, meeting EPA precision and recovery criteria. Carry-over tests after high-concentration runs showed only trace 6:2 FTS at 0.07 ng/g, well below the method MDL, confirming effective single-rinse cleaning.

Přínosy a praktické využití metody

The integrated ASE-SPE workflow significantly reduces sample handling by automating extraction, elimination of evaporation and filtration steps, and combining cleanup in a single operation. This increases throughput, reduces hands-on time and potential contamination, and delivers high analytical accuracy and reliability. The method fulfils stringent regulatory limits for environmental PFAS monitoring and suits high-throughput laboratories engaged in QA/QC and remediation studies.

Budoucí trendy a možnosti využití

Further automation could enable continuous processing of larger sample batches and integration with high resolution mass spectrometry for expanded compound coverage. Miniaturization of extraction cells and on-line cleanup may reduce solvent usage. Adapting the workflow to other solid matrices such as biosolids and sediments or coupling to non-target screening by high-resolution MS will support comprehensive PFAS surveillance and emerging regulatory needs.

Závěr

The semi-automated method using the EXTREVA ASE and AutoTrace 280 PFAS systems offers a robust, efficient approach for soil PFAS analysis according to EPA Method 1633A. It delivers low detection limits, strong linearity, excellent recoveries, minimal carry-over, and reduced manual operations, making it an effective solution for environmental laboratories tasked with PFAS monitoring.

Reference

1. Velez MP et al Human Reproduction 2015 30 701–709
2. US EPA Method 1633A Analysis of PFAS in solids by LC-MS/MS EPA 2023
3. Ullah R et al Advances in Sample Preparation 2023 DOI 10.1016/j.sampre.2023.100073
4. Thermo Fisher Scientific AN73883 Determination of PFAS in drinking water 2020
5. Thermo Fisher Scientific AN002771 LC-MS/MS analysis of PFAS in soils 2024
6. US EPA MDL Definition and Procedure Revision 2 2016