The quantitative power of high-resolution GC-Orbitrap mass spectrometry for the analysis of pesticides and PCBs in food

Significance of the Topic

The accurate determination of pesticide residues and PCBs in food is vital for regulatory compliance and public health protection. In the European Union, default maximum residue levels are often set at 10 µg/kg, demanding highly sensitive and selective analytical methods. High-resolution accurate-mass gas chromatography–Orbitrap mass spectrometry enables full-scan untargeted acquisition, superior selectivity, and the ability to perform retrospective data analysis for comprehensive monitoring.

Study Objectives and Overview

This work evaluates the quantitative performance of the Exactive GC Orbitrap mass spectrometer for the analysis of 88 pesticides and 7 PCB congeners in grape and onion matrices. The study focuses on sensitivity (limits of detection), linearity, response factor stability, precision, and accuracy in accordance with EU regulatory criteria.

Methodology and Instrumentation

Grape and onion samples were cryogenically homogenized and extracted using a mini-Luke procedure involving acetone, dichloromethane, petroleum ether, and sodium sulfate. Extracts underwent rotary evaporation and solvent exchange into ethyl acetate. Matrix-matched calibration standards (1–200 µg/kg) and blind-spiked samples (0.5–100 µg/kg) were prepared.
Instrumentation Used

• TriPlus RSH autosampler for automated injection
• TRACE 1310 GC system with a 30 m × 0.25 mm ID, 0.25 µm film TraceGOLD TG-5SilMS capillary column with integrated guard
• Exactive GC Orbitrap mass spectrometer in electron ionization full-scan mode at 60 000 resolution (FWHM at m/z 200)
• Helium carrier gas at 1.2 mL/min, splitless programmable temperature vaporization
• TraceFinder software for acquisition, extracted ion chromatograms (±5 ppm window), and quantitation

Key Findings and Discussion

• Limits of detection were ≤2 µg/kg for 92 of 95 analytes; three compounds exhibited LODs of 5 µg/kg, all below EU MRLs.
• Linearity across 1–200 µg/kg delivered R² > 0.99 and response factor RSD < 20% for every compound.
• Blind-spiked samples yielded calculated concentrations closely matching spiked values, demonstrating accurate quantitation.
• A fivefold dilution study confirmed detection of captan at sub-µg/kg levels in complex matrices.
• Full-scan acquisition provided flexibility for retrospective screening beyond the initial target list without additional method setup.

Benefits and Practical Applications

This GC-Orbitrap workflow simplifies method development by removing the need for predefined reaction monitoring transitions. It supports untargeted and retrospective analysis, robust routine QA/QC performance, and compliance with stringent regulatory guidelines, all with minimal maintenance due to the integrated guard column.

Future Trends and Opportunities

Ongoing advances in high-resolution GC-MS will expand capabilities for non-target and suspect screening of emerging contaminants. Integration with automated sample preparation, machine-learning-driven data processing, and multi-class workflows will enhance throughput and analytical scope, enabling simultaneous monitoring of pesticides, PCBs, and other organic pollutants.

Conclusion

The Exactive GC Orbitrap mass spectrometer delivers sensitive, accurate, and precise quantitation of pesticides and PCBs in fruit and vegetable matrices. Its full-scan untargeted approach meets regulatory requirements, provides analytical flexibility, and supports comprehensive residue analysis in food safety laboratories.

References

1. European Commission. Guidelines for Pesticide Maximum Residue Levels. Plant Health and Pesticides.
2. SANTE/11945/2015. Guidance Document on Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed.
3. Mol H, Tienstra M, Zomer P. Evaluation of GC–Electron Ionization Full-Scan High-Resolution Orbitrap Mass Spectrometry for Pesticide Residue Analysis? Analytica Chimica Acta. 2016;935:161–172.
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5. Thermo Fisher Scientific. Application Note 10448. Broad-Scope Screening of Pesticides Using GC High-Resolution Orbitrap Mass Spectrometry. 2016.
6. Thermo Fisher Scientific. Application Note 10509. Routine Quantitative Method for Pesticides Using GC-Orbitrap in Accordance with SANTE/11945/2015. 2016.
7. Thermo Fisher Scientific. Application Note 10541. Multi-Residue Pesticide Screening in Cereals Using GC-Orbitrap. 2017.
8. Lozano A, Kiedrowski B, Scholten J, de Kroon M, de Kok A, Fernández-Alba AR. Miniaturisation and Optimisation of the Dutch Mini-Luke Extraction for Routine Multi-Residue Analysis of Pesticides in Fruits and Vegetables. Food Chemistry. 2016;192:668–681.
9. Thermo Fisher Scientific. Orbitrap GC-MS Product Information.