Quantitative analysis of environmental contaminants using Orbitrap Exploris GC

Significance of the Topic

Food safety monitoring requires sensitive and reliable detection of trace environmental contaminants such as pesticides, PCBs, PAHs, and BFRs. High-throughput laboratories face pressure to deliver rapid results across expanding target lists and diverse food matrices. High-resolution accurate mass (HRAM) spectrometry coupled with gas chromatography simplifies method development, enhances selectivity, and enables retrospective data analysis, addressing the limitations of traditional GC-MS/MS workflows.

Objectives and Study Overview

The study evaluates the Thermo Scientific Orbitrap Exploris GC mass spectrometer paired with a TRACE 1310 GC to determine its quantitative performance for persistent organic pollutants (POPs) in food matrices. It compares sensitivity, linearity, and quantitation accuracy with those obtained by a conventional triple quadrupole GC-MS/MS, using proficiency test materials and real sample analyses.

Methods and Instrumentation

• Sample extraction: Accelerated solvent extraction (ASE) or Soxhlet extraction with 13C-labeled or deuterated internal standards.
• Cleanup: Deactivated Florisil silica, SPE silica, or sulfuric acid silica for fat-rich samples; final extract in toluene.
• Chromatography: Thermo Scientific TRACE 1310 GC with TraceGOLD TG-5SilMS column (30 m × 0.25 mm i.d., 0.25 μm film) and TriPlus RSH autosampler.
• Detection: Orbitrap Exploris GC mass spectrometer in full-scan mode (m/z 50–600) at 60 000 resolution (FWHM at m/z 200) with ExtractaBrite EI source.
• Data processing: Thermo Scientific Chromeleon CDS with pre-optimized templates; extracted ion chromatograms with ±5 ppm mass window.

Results and Discussion

• Linearity: R² ≥ 0.995 for most analytes; PCBs achieved R² ≥ 0.9999 across 0.005–11 pg/µL.
• Sensitivity: Limits of quantitation (LOQs) below 0.1 pg/µL for OCPs and PCBs, < 1 pg/µL for BFRs; PAH precision at 1 pg/µL better than 10%.
• Chromatographic selectivity: Effective isobaric separation of key PBDE congeners to avoid mass spectral overlaps.
• Quantitative accuracy: Proficiency tests yielded z-scores within ± 2 for EU priority PAHs, PCBs, and BFRs in olive oil and fish fillet samples.
• Comparison with GC-MS/MS: Orbitrap Exploris GC provided comparable or improved quantitative performance and reliable results for real sample matrices.

Benefits and Practical Applications

• Streamlined full-scan acquisition simplifies method setup and allows retrospective screening of additional compounds.
• High resolution and mass accuracy improve selectivity and reduce false positives in complex matrices.
• Pre-optimized templates and intuitive software enable walk-up operation and increased throughput.
• Consolidation of multiple compound classes into a single analytical workflow reduces instrument downtime.

Future Trends and Applications

High-resolution GC-MS workflows are expected to expand with:

• Integration of larger compound databases for comprehensive environmental screening.
• Advances in data analysis software with automated identification and quantitation algorithms.
• Increased instrument resolving power to tackle ultra-trace analytes and isomeric interferences.
• Miniaturized and high-throughput extraction techniques aligned with green chemistry principles.

Conclusion

The Orbitrap Exploris GC system demonstrated robust sensitivity, linearity, and quantitative accuracy for a broad range of environmental contaminants in food samples. Its high-resolution full-scan capability, combined with streamlined workflows, positions it as a reliable alternative to triple quadrupole GC-MS/MS for routine and research applications in food safety laboratories.

References

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