Contaminants Screening Using High‑Resolution GC/Q-TOF and an Expanded Accurate Mass Library of Pesticides and Environmental Pollutants

Significance of the Topic

The detection of pesticide residues and environmental contaminants in food matrices is critical for consumer safety and regulatory compliance. High-resolution GC/Q-TOF offers the sensitivity, specificity, and broad scope needed to screen for hundreds of compounds in a single run. By leveraging accurate mass measurements and retention time locking, laboratories can minimize false positives and negatives while accelerating data review.

Objectives and Study Overview

This study demonstrates a streamlined workflow that integrates broad-scope suspect screening and targeted quantitation of over 1,000 pesticides and environmental pollutants. Strawberry extracts from organic and nonorganic sources were analyzed to validate compliance with SANTE/11945/2015 guidelines and to compare performance between high-resolution GC/Q-TOF and traditional GC/MSD methods.

Methodology

Sample preparation followed the EN QuEChERS protocol with dispersive SPE cleanup. Chromatographic separation employed an Agilent 8890 GC with a midcolumn backflush and retention-time locking to chlorpyrifos-methyl (RT 18.111 min). Data were acquired on an Agilent 7250 GC/Q-TOF (m/z 45–650, 5 Hz) and an Agilent 5977B GC/MSD in full-spectrum mode. GC/Q-TOF data were processed in MassHunter Quantitative Analysis 10.1 using the SureMass format. Screening parameters were optimized as follows:

• Mass accuracy: ±5 ppm
• RT window: ±0.05 min
• Library match score threshold: 75
• Coelution and fragmentation scores per SANTE guidelines

Used Instrumentation

• Agilent 8890 Gas Chromatograph with pneumatic switching device (midcolumn backflush)
• Agilent 7250 GC/Q-TOF Mass Spectrometer
• Agilent 5977B GC/MSD Mass Spectrometer
• Agilent MassHunter Quantitative Analysis Software 10.1

Main Results and Discussion

Nonorganic strawberry extracts contained 10–20 pesticide residues per sample, with frequent detections of flonicamid, pyrimethanil, cyprodinil, fluopyram, fludioxonil, captan, and bifenthrin. Organic samples showed only trace-level residues. GC/Q-TOF consistently identified more compounds than GC/MSD and achieved comparable quantitation (e.g., cyprodinil: GC/Q-TOF 21 ppb vs. GC/MSD 18–23 ppb). The high-resolution workflow also eliminated false positives (e.g., ethiofencarb was flagged by GC/MSD but not confirmed by accurate mass data).

Benefits and Practical Applications

This integrated approach delivers:

• Simultaneous suspect screening and quantitation in one software environment
• Enhanced confidence through accurate mass and RT locking
• Reduced data processing time and manual review
• Broad-scope capability without individual calibrations

Laboratories performing food safety, environmental, or industrial quality control analyses can adopt this workflow to improve throughput and reliability.

Future Trends and Potential Applications

Emerging developments include further expansion of accurate mass libraries, incorporation of machine-learning algorithms for automated data review, extension to other complex matrices (e.g., soil, water, biological fluids), and integration with ambient ionization techniques. Growing regulatory acceptance of high-resolution screening methods will drive broader adoption in routine QA/QC and surveillance programs.

Conclusion

The described high-resolution GC/Q-TOF workflow, combined with an expanded accurate mass library, provides a robust, efficient, and reliable solution for multiresidue pesticide and contaminant screening in food. It outperforms unit-mass techniques by reducing false positives and negatives, streamlining data processing, and offering quantitative results in a single run.

References

1. SANTE/11945/2015 Guidance Document on Analytical Quality Control and Method Validation Procedures for Pesticide Residues in Food and Feed (2015).
2. USDA Pesticide Data Program Annual Summary Reports (2016).
3. Andrianova, A. A.; Quimby, B. D.; Westland, J. L. “GC/MSD Pesticide Screening in Strawberries at Tolerance Levels Using Library Searching of Deconvoluted Spectra.” Agilent Technologies Application Note 5994-0915EN.
4. US EPA Office of Pesticide Programs. Index to Pesticide Chemical Names, Part 180 Tolerance Information (2012).
5. Chen, K.; Nieto, S.; Stevens, J. “GC/Q-TOF MS Surveillance of Pesticides in Food: A Combined Workflow for Quantitative and Qualitative Screening.” Agilent Technologies Application Note 5991-7691EN.