PESTICIDES - Analysis by GC/LC/Sample Prep

Importance of the Topic

Pesticide residues in food and environmental samples require highly robust, sensitive, and selective analytical workflows to ensure consumer safety and regulatory compliance.

Goals and Overview of the Study

This application series demonstrates versatile methods for pesticide analysis covering:

• Polar analytes such as glyphosate and AMPA
• Comprehensive multi-class screenings
• Neonicotinoids in honey
• Pesticides in leafy matrices
• Chlorinated pesticides by GC/ECD

Methodology and Instrumentation

• Sample Preparation: QuEChERS protocols (AOAC 2007.01, EN 15662) with dispersive SPE clean-up using MgSO4, PSA, C18, and GCB sorbents.
• Chromatography: UHPLC columns including Luna NH2 (HILIC), Gemini NX-C18 (FMOC derivatization), Kinetex core-shell (biphenyl, EVO F5), Synergi Fusion-RP.
• Gas Chromatography: Zebron ZB-5MSi and MultiResidue columns for broad screening; specialized ZB-CLPesticides phases for chlorinated compounds.
• Detection: Tandem mass spectrometers (AB SCIEX API 5000, 4500 QTRAP, 3200, 4000) with ESI-, GC/MSD, and GC/ECD platforms.

Main Results and Discussion

• Glyphosate and AMPA: Both underivatized HILIC and FMOC derivatization modes achieved sharp peaks and baseline resolution at alkaline pH.
• Broad-spectrum LC/MS/MS: Core-shell biphenyl columns provided enhanced polar retention for over 175 pesticides; Fusion-RP columns screened 535 compounds in under 18 minutes with high reproducibility.
• Neonicotinoids in Honey: QuEChERS sample prep and Kinetex biphenyl separation yielded clean chromatograms for eight residues at 400 ng/g levels.
• Pesticides in Spinach: AOAC QuEChERS followed by GC/MS and LC/MS/MS allowed quantitation of 23 analytes spiked at 200 ng/g with robust performance.
• Chlorinated Pesticides by GC/ECD: ZB-CLPesticides phases separated 22 organohalides with high sensitivity and selectivity.

Benefits and Practical Applications

• Comprehensive coverage of polar and nonpolar pesticide classes.
• High throughput with reduced analysis time and solvent consumption.
• Reproducible sample preparation using modular QuEChERS kits.
• Regulatory compliance through sensitive MS/MS and ECD detection.

Future Trends and Opportunities

• Development of faster UHPLC methods and core-shell technologies for greater speed and resolution.
• Expanding the pH stability window of stationary phases for challenging analytes.
• Automation of sample prep workflows, including inline SPE and robotics.
• Integration of high-resolution MS for non-targeted screening and metabolite profiling.

Conclusion

The documented workflows integrate advanced sample preparation, UHPLC, GC, and MS techniques to deliver versatile, reproducible, and selective pesticide analysis. These methods address diverse matrices and meet stringent regulatory requirements.