Analysis of Multiple Pesticide Residues in Fruits and Vegetables using GC/Q-TOF and EI Accurate Mass Pesticide Library

Significance of the Topic

Ensuring global food safety requires comprehensive detection of pesticide residues in produce. With over 900 approved pesticides and strict regulatory limits worldwide, advanced analytical methods are essential for reliable monitoring and compliance. High-resolution GC/Q-TOF combined with accurate mass libraries addresses the need for untargeted screening, high sensitivity, and confidence in identification throughout complex matrices.

Objectives and Study Overview

This study demonstrates a workflow integrating a novel accurate mass pesticide library with GC/Q-TOF for the simultaneous screening and quantitation of more than 100 pesticides in peach and avocado matrices. Key aims include assessing screening capability at low concentrations, evaluating mass accuracy, retention time stability, and establishing a broad dynamic range calibration.

Methodology and Instrumentation

• Sample Preparation: Peach samples extracted using AOAC QuEChERS with dispersive SPE cleanup; avocado samples processed by EN QuEChERS followed by EMR-Lipid cleanup to reduce lipid interference.
• Spiking and Calibration: 120 pesticide standards spiked at 5–200 ng/mL to assess screening and calibration performance.
• GC/Q-TOF Analysis: Agilent 7200 Series GC/Q-TOF in EI full-scan mode with mid-column backflushing; 20 min constant-flow retention time locked method on HP-5 MS UI columns; data acquired at 45–550 m/z, 4 GHz, 5 spectra/sec.
• Data Processing: Automated identification via MassHunter Find by Fragment using a curated library of 800+ compounds; qualified ions transferred into MassHunter Quantitative Analysis for calibration.

Main Results and Discussion

• Screening Performance: At 5 ng/mL, 118 of 120 pesticides detected automatically and up to 120 at 10 ng/mL; manual extraction added a few low-signal compounds.
• Retention Time Stability: SD ≤ 0.01 min for most analytes, confirming robust retention time locking.
• Response Precision: Single-digit percent RSD for trace-level responses (n=6) and stable long-term repeatability across 36 injections.
• Mass Accuracy and Ion Ratio: Over 90% of pesticides exhibited ion ratio variances within ±30% versus library spectra; more than 90% showed mass errors < 5 ppm in both matrices.
• Dynamic Range Calibration: Matrix-matched calibration from 5 to 200 ng/mL achieved R² > 0.99 for 105 pesticides using a profile-based algorithm (SureMass).

Benefits and Practical Applications

• Enhanced Confidence: High-resolution accurate mass data improve specificity and reduce false positives in complex food extracts.
• Untargeted Screening: Full-scan acquisition allows retrospective analysis for emerging pesticides without prior method changes.
• Efficient Workflows: Combined automated screening and quantitation in a single run enhances laboratory throughput and compliance monitoring.

Future Trends and Applications

• Expansion of Accurate Mass Libraries to include novel and degradate compounds.
• Integration with machine learning for automated anomaly detection and trend analysis.
• Development of real-time or near-real-time monitoring platforms for on-site food safety testing.
• Standardization of high-resolution GC/MS methods across regulatory agencies for harmonized compliance.

Conclusion

The combined use of GC/Q-TOF and an accurate mass pesticide library provides a robust, high-throughput solution for broad-scope pesticide residue screening and quantitation in complex food matrices. The method delivers excellent mass accuracy, retention time stability, and dynamic range, supporting regulatory compliance and food safety assurance.