Analysis of PFAS and Other Environmental Contaminants in Soil and Oat Plants Using High-Resolution GC/Q-TOF

Importance of the Topic

Soil and plants act as reservoirs and conduits for per- and polyfluoroalkyl substances (PFAS) and other persistent organic pollutants. PFAS in soil can migrate to groundwater and enter food chains, while shorter-chain volatile PFAS, increasingly used as long-chain substitutes, are underreported by standard LC/MS methods. Complementary high-resolution GC/Q-TOF approaches enhance detection and profiling of a broader PFAS spectrum and co-occurring contaminants.

Study Objectives and Overview

This work evaluates extraction and screening strategies for PFAS and diverse environmental pollutants in soil and oat plants. Key goals include comparison of methylene chloride extraction versus headspace solid-phase microextraction (HS-SPME), deployment of a PFAS accurate mass personal compound database and library (PCDL) for targeted screening, and combined nontarget workflows for PCBs, PBDEs, pesticides, PAHs, and flame retardants.

Instrumentation

• Agilent 7250 GC/Q-TOF mass spectrometer
• Agilent 8890 gas chromatograph with multimode inlet
• Agilent J&W DB-624 and DB-5ms UI GC columns
• Agilent PAL 3 CTC autosampler for HS-SPME

Methodology

Soil and oat plants were sampled from biosolid-amended and organic fields at pre-application and harvest stages. Samples underwent either methylene chloride extraction or HS-SPME with optimized fibers (DVB/CWR/PDMS) and conditions. GC/Q-TOF full-spectrum data were acquired on DB-624 for PFAS screening and DB-5ms for broader target/nontarget analysis. Targeted screening used PFAS and pesticide PCDLs with retention index confirmation; nontargeted analysis applied SureMass deconvolution and NIST 23 library searches with ExactMass validation.

Main Results and Discussion

HS-SPME with PFAS PCDL screening achieved highest sensitivity for volatile PFAS, identifying compounds such as 6:2 fluorotelomer alcohol and ethyl perfluorobutyl ether across soil and plant extracts. Nontargeted workflows detected 20 PCBs and PBDEs in soils, pesticides (over 50 compounds) in biosolid-treated soils, phenanthrene and fluoranthene in both matrices, and a suite of flame retardants, including tributyl phosphate and tris(3-chloropropyl) phosphate.

Practical Benefits and Applications

• Enhanced PFAS coverage beyond 40–80 analytes by LC/MS methods
• Integrated target/nontarget screening in single GC/Q-TOF runs
• Automated, high-throughput workflows reducing manual validation
• Quantitative and qualitative insight into co-contaminant profiles

Future Trends and Application Opportunities

• Expansion of accurate mass libraries to emerging PFAS and transformation products
• Integration with isotopic dilution for quantitation of low-level PFAS
• Coupling GC/Q-TOF with multidimensional separations for isomer resolution
• Adoption of machine learning for automated spectral deconvolution and identification

Conclusion

High-resolution GC/Q-TOF combined with HS-SPME and targeted PCDL screening offers a robust, sensitive platform for comprehensive analysis of volatile PFAS and co-existing environmental contaminants in soil and plant matrices. The integration of targeted and nontargeted workflows streamlines data acquisition and expands the scope of detectable pollutants.

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