Applying high resolution GC-Orbitrap mass spectrometry for the quantitative analysis of environmental contaminants in food

Significance of High-Resolution GC-Orbitrap MS for Trace Contaminant Analysis

This work highlights the importance of sensitive, selective, and high-throughput methods in food and environmental testing laboratories. High-resolution mass spectrometry (HRMS) expands analytical scope while maintaining rapid turnaround and reliable quantitation for complex matrices.

Objectives and Study Overview

The study evaluated the Thermo Scientific Orbitrap Exploris GC mass spectrometer for quantifying pesticides, PCBs, PAHs, and brominated flame retardants (BFRs) in food and environmental samples. Performance metrics were compared to those from a conventional triple quadrupole GC-MS system using proficiency test samples.

Methodology and Instrumentation Used

Sample Preparation:

• Accelerated solvent extraction or Soxhlet with 13C-labeled or deuterated internal standards.
• Cleanup via Florisil™-silica, SPE silica, or sulfuric acid silica, depending on matrix.
• Final solvent: toluene.

GC-HRMS Parameters:

• Autosampler: TriPlus™ RSH
• GC: TRACE™ 1310 with TraceGOLD™ TG-5SilMS column (30 m × 0.25 mm × 0.25 µm).
• MS: Orbitrap Exploris GC, full-scan mode at 60,000 resolution (m/z 200).

Comparison System:

• TSQ™ 9610 triple quadrupole GC-MS/MS, SRM mode for targeted quantitation.

Data Processing:

• Chromeleon CDS software for instrument control, method development, and quantitation.

Results and Discussion

Linearity and Sensitivity:

• PCBs: R2 ≥ 0.9999 over 0.005 to 11 pg/µL; LOQs < 0.1 pg/µL.
• BFRs: R2 > 0.995; LOQs < 1 pg/µL.
• PAHs: R2 > 0.995; precision < 10% at 1 pg/µL with internal standard correction.

Proficiency Testing:

• Analyzed EU and Fapas proficiency samples (olive oil, fish fillet).
• Orbitrap Exploris GC results matched assigned values with z-scores |z| ≤ 2, comparable to triple quadrupole.

Comparison to Triple Quadrupole:

• Full-scan HRMS allowed untargeted acquisition and retrospective data mining.
• Quantitative performance equivalent to triple quadrupole instruments across multiple compound classes.

Benefits and Practical Applications

The GC-Orbitrap Exploris GC:

• Offers broad-spectrum quantitative analysis in a single run.
• Simplifies method setup by avoiding compound-specific SRM optimization.
• Enables retrospective screening for unexpected contaminants.
• Supports high throughput with robust sensitivity and linearity.

Future Trends and Opportunities

High-resolution GC-MS is poised to:

• Integrate multi-class contaminant screening workflows.
• Leverage data-rich full-scan acquisitions for non-targeted and suspect screening.
• Adopt machine learning for automated peak identification and quantitation.
• Combine HRMS with advanced sample preparation for ultra-trace analysis in complex matrices.

Conclusion

The Orbitrap Exploris GC mass spectrometer demonstrates exceptional performance for trace analysis of pesticides, PCBs, PAHs, and BFRs in food and environmental samples. Its high resolution, full-scan capability, and quantitative accuracy match or exceed traditional triple quadrupole systems, enabling more flexible and comprehensive analytical workflows.

Reference

Rajski L., Haas D., Roberts D. Applying high resolution GC-Orbitrap mass spectrometry for the quantitative analysis of environmental contaminants in food. Thermo Fisher Scientific application note, 2022.