High Efficiency, Broad Scope Screening of Pesticides Using Gas Chromatography High Resolution Orbitrap Mass Spectrometry

Importance of the Topic

Pesticide residues in food and feed must be monitored to protect consumer health and comply with regulatory maximum residue limits (MRLs). High-throughput, broad-scope screening methods are essential to detect hundreds of pesticides in complex matrices quickly and reliably, minimizing false negatives and enabling retrospective analysis of unexpected contaminants.

Objectives and Overview of the Study

This study evaluates a full-scan, high-resolution Orbitrap mass spectrometry approach for the rapid screening of 183 gas-chromatography-amenable pesticides. The goal was to determine if residues could be detected at or below typical MRL levels (e.g., 10 ng/g) in challenging sample types such as wheat, horse feed, and leek, using a single 17-minute chromatographic run.

Methodology and Instrumentation Used

Samples were prepared by a QuEChERS-based extraction (acidified acetonitrile, salt partitioning, centrifugation) and spiked with pesticide standards. Key instrumentation:

• Thermo Scientific TRACE 1310 gas chromatograph with 15 m×0.25 mm×0.25 µm TraceGOLD TG-5SilMS column
• Thermo Scientific TriPlus RSH autosampler
• Q Exactive GC hybrid quadrupole-Orbitrap mass spectrometer operated in EI full-scan mode (50–500 Da) at 60,000 resolving power (m/z 200)
• TraceFinder software for data acquisition, screening, and quantification

Main Results and Discussion

• All 55 target pesticides were detected at 10 ng/mL in wheat, feed, and leek; 47 compounds were still detected at 0.5 ng/mL in wheat.
• Mass accuracy consistently below 2 ppm (often sub-ppm) enabled confidence in identifying both molecular ions and fragments.
• At lower resolution (15K–30K), co-eluting matrix interferences distorted accurate mass measurements, but 60K FWHM resolved these overlaps to avoid false negatives.
• Fast GC method (17 min) with ≥11 data points/peak supports high throughput (up to 84 injections/day).
• Calibration curves in matrix showed excellent linearity (R² > 0.99) over 0.5–50 ng/mL.

Benefits and Practical Applications

• Comprehensive screening of hundreds of pesticides in a single injection without compound-specific parameter optimization.
• High resolving power and mass accuracy reduce false negatives and false positives, especially in complex matrices.
• Rapid turnaround and software-assisted data review streamline routine QA/QC workflows in food safety laboratories.

Future Trends and Opportunities

Advances in hybrid high-resolution mass spectrometry and data processing will further expand non-targeted screening capabilities. Integration of retrospective data mining will allow identification of emerging contaminants. Continued development of robust, automated workflows will improve laboratory efficiency and regulatory compliance.

Conclusion

The Q Exactive GC Orbitrap system combined with TraceFinder software provides a reliable, high-throughput solution for broad-scope pesticide screening, delivering excellent sensitivity, mass accuracy, and resolving power to meet stringent regulatory requirements.

References

1. SANCO/12571/2013. Method validation and quality control procedures for pesticides residue analysis in food and feed. European Commission.
2. Kellmann M., Münster H., Zomer P., Mol H. (2009) Full Scan MS in comprehensive qualitative and quantitative residue analysis in food and feed matrices: how much resolving power is required? Journal of the American Society for Mass Spectrometry, 20, 1464–1476.
3. Thermo Scientific Application Note 10449. Fast screening, identification, and quantification of pesticide residues in baby food using GC Orbitrap MS technology. Thermo Fisher Scientific, Runcorn, UK.