Pesticide residues analysis for commercial food testing laboratories

Importance of the Topic

Ensuring the safety of the food supply requires reliable, sensitive, and high-throughput methods to detect and quantify pesticide residues across diverse food matrices. Regulatory bodies worldwide set maximum residue levels (MRLs) to protect consumers, and testing laboratories must meet stringent validation criteria while maintaining productivity and robustness.

Study Objectives and Overview

This compendium presents a suite of innovative analytical workflows developed by Thermo Fisher Scientific to support commercial food testing laboratories in multi-residue pesticide analysis. The methods target hundreds of compounds in sample types ranging from baby food, fruits, vegetables, cereals, rice, wheat, chili powder, eggs, milk, and wine. All protocols were validated in accordance with EU SANTE guidelines and other global regulatory requirements to ensure compliance and performance.

Methodology and Instrumentation

Sample preparation strategies:

• QuEChERS extraction with citrate or acetate buffering for broad-spectrum residue recovery.
• Dispersive SPE (dSPE) and automated micro-SPE (μSPE) clean-up to reduce matrix interferences and increase throughput.
• Modified protocols for specific matrices (e.g., graphitized carbon black for chili powder, C18/PSA for milk).

Chromatographic separation and mass spectrometry platforms:

• Gas chromatography–triple quadrupole MS/MS (TSQ 8000 Evo, TSQ 9000) with Advanced Electron Ionization or ExtractaBrite sources for ultra-trace detection.
• GC-Orbitrap HRAM (Exactive GC, GC Orbitrap) enabling full-scan accurate-mass screening and quantitation of >100 pesticides and PCBs.
• Liquid chromatography–tandem MS (Vanquish Flex, Accucore aQ, Hypersil GOLD columns) for >400 multi-class pesticides at sub-ppb levels.
• Ion chromatography–MS/MS for polar anionic and cationic pesticides using Dionex Integrion RFIC and high-resolution Orbitrap systems.

Data acquisition and processing:

• Integrated software solutions (TraceFinder, Chromeleon CDS, Freestyle, Compound Discoverer) for streamlined instrument control, targeted quantitation, and post-acquisition screening.
• Advanced workflows (AcquireX) for automated inclusion/exclusion list generation and dynamic data-dependent acquisition.

Key Findings and Discussion

Across all methods, laboratories achieved:

• Sensitivity well below regulatory MRLs (down to 0.001–0.01 mg/kg) with excellent limits of detection and quantitation.
• Wide dynamic linear ranges (up to five orders of magnitude) and correlation coefficients (R² > 0.99).
• Robust performance over hundreds of consecutive injections, maintaining retention time stability and consistent ion ratios.
• High recoveries (70–120%) and precision (%RSD < 20%) in complex matrices, meeting or exceeding SANTE quality criteria.
• Increased throughput via minimized run times (8–15 minutes per injection), automation of clean-up, and reduced sample handling.

Practical Benefits and Applications

The validated workflows deliver tangible advantages for commercial testing laboratories:

• Regulatory compliance with EU and global MRLs, ensuring data defensibility.
• Enhanced productivity through automation (μSPE, online SPE, robotic sampling) and fast acquisition cycles.
• Flexibility to expand target lists post-acquisition using full-scan HRAM data without re-running samples.
• Reduced maintenance and downtime by diluting extracts, employing robust ion sources, and utilizing vacuum probe interlock technologies.
• Comprehensive coverage of pesticides, metabolites, and isomers in a single run.

Future Trends and Potential Applications

Emerging directions in pesticide residue analysis include:

• Deeper integration of high-resolution MS for non-targeted screening and retrospective data mining.
• Further miniaturization and green sample-preparation techniques to reduce solvent use and waste.
• Artificial intelligence and machine learning for automated peak detection, anomaly flagging, and method optimization.
• Multi-dimensional separations (e.g., GC×GC-MS/MS, LC-IC hyphenation) for ultra-complex matrices.
• Deployment of portable and in-field mass spectrometers for rapid screening at the point of harvest or processing.

Conclusion

The Thermo Fisher Scientific compendium demonstrates that combining optimized sample-preparation protocols, advanced chromatographic separations, and cutting-edge mass spectrometry platforms enables commercial food testing laboratories to meet the growing demands for sensitivity, throughput, and regulatory compliance in pesticide residue analysis. Continuous innovation in automation, high-resolution detection, and data-processing workflows will further enhance laboratory capabilities and ensure the safety and integrity of the global food supply.

References

Lozano A., Kiedrowsk B., Scholten J., de Kroon M., de Kok A., Fernández-Alba A.R. Miniaturisation and optimisation of the Dutch mini-Luke extraction method for multi-residue analysis of pesticides in fruits and vegetables. Food Chem. 2016, 192, 668–681.