Accurately Identify and Quantify A Hundred Pesticides in a Single GC Run

Significance of the Topic

Pesticide residue analysis is critical for ensuring food safety and compliance with regulatory limits. Modern agricultural practices employ hundreds of chemical compounds, and analytical laboratories face the challenge of identifying and quantifying dozens to hundreds of these residues in a single chromatographic run. Adopting high-throughput screening approaches is essential to maintain sensitivity, accuracy and laboratory efficiency.

Objectives and Study Overview

This study compares traditional time-segmented multiple reaction monitoring (TS-MRM) with dynamic MRM (dMRM) in a fast, multi-analyte GC-MS/MS workflow. A target list of 195 pesticides was evaluated in various food matrices using both a 40-minute resolution method and a 20-minute fast-analysis method. The goal was to assess method setup time, data quality, sensitivity and throughput.

Methodology and Instrumentation

The analysis employed an Agilent 7890B gas chromatograph coupled to a 7010 Triple Quadruple mass spectrometer. A multimode inlet with an ultra-inert liner facilitated hot splitless injections (1 µL) at 280 °C, using helium as the carrier gas (1.00 mL/min). Two 15 m × 0.25 mm × 0.25 µm HP-5ms UI columns were connected via a purged ultimate union for backflushing. Oven programs compared a 40 min (40 °C/min to 120 °C, 5 °C/min to 310 °C) and a 20 min (40 °C/min to 170 °C, 10 °C/min to 310 °C) temperature gradient.

• MS source temperature: 300 °C; quadrupole temperature: 150 °C
• Electron energy: 70 eV; collision gases: N₂ (1.5 mL/min) and He (2.25 mL/min)
• TS-MRM used fixed dwell times (~5 scans/s overall); dMRM dwell times were optimized dynamically

Key Findings and Discussion

dMRM reduced method development time by allowing rapid selection or import of compounds and transitions, with automated retention time windowing and dwell-time optimization. Both TS and dMRM workflows achieved comparable sensitivity for low-level pesticide residues, but dMRM supported more efficient cycle times when monitoring nearly 600 transitions. The 20 min fast method combined with dMRM maintained analyte separation and quantitation quality similar to the longer run.

Benefits and Practical Applications

• Higher throughput: ability to quantify hundreds of analytes in a single GC run without sacrificing sensitivity
• Streamlined method setup: dynamic scheduling and database integration reduce manual steps
• Flexibility: quick adjustment of retention time windows and dwell times for different matrices
• Applicable to regulatory, QA/QC and research laboratories handling complex food and environmental samples

Future Trends and Opportunities

Advances in software-driven scheduling and deeper integration with compound databases will further accelerate multi-residue methods. Emerging gas chromatography sources and enhanced ion optics promise improved sensitivity, enabling even faster run times. Machine learning–based prediction of retention times and collision energies could automate method optimization for new analytes.

Conclusion

This evaluation demonstrates that dynamic MRM on a GC-MS/MS platform offers a robust, high-throughput solution for pesticide residue analysis. By coupling fast temperature programs with automated transition scheduling, laboratories can reliably meet the demands of large-scale screening with minimal compromise in data quality.

References

Westland J, Doherty T, Chen V. Accurately Identify and Quantify A Hundred Pesticides in a Single GC Run. ASMS 2016 Poster TP215.