NACRW 2017: Routine quantitative method of analysis for pesticides using GC-Orbitrap mass spectrometry in accordance with SANTE/11945/2015 Guidance

Importance of Topic

Pesticide residues in food pose significant health and regulatory concerns. High‐resolution mass spectrometry with full‐scan capability allows broad‐scope detection and robust quantification to meet stringent SANTE guidelines for routine quality assurance in fruits and vegetables.

Study Objectives and Overview

This work aimed to establish a routine quantitative protocol for 51 pesticide residues using a GC‐Orbitrap MS platform. Objectives included achieving low limits of detection and identification, excellent mass accuracy, high throughput, and adherence to SANTE/11945/2015 performance criteria across tomato, leek and orange matrices.

Methodology and Instrumentation

• Sample Preparation: Acetate‐buffered QuEChERS extraction, PSA cleanup, spiking of blank matrix at 0.5–500 µg/kg levels.
• Chromatography: Thermo TRACE 1310 GC with single‐taper liner, 1 µL injection, He carrier gas at 1.2 mL/min, gradient from 40 °C to 300 °C.
• Mass Spectrometry: Exactive GC Orbitrap MS, full‐scan 50–550 m/z, EI 70 eV, resolving power 60,000 FWHM, lockmass at m/z 207.03235.
• Data Processing: Thermo Scientific TraceFinder software for automatic identification, calibration (R2>0.99), mass accuracy filtering (<5 ppm at LOI).

Key Results and Discussion

• Limits: 93% of pesticides detected at ≤1 µg/kg; all but chlorothalonil met LOI ≤5 µg/kg.
• Mass Accuracy: Sub‐ppm RMS accuracy per scan; full‐scan at 60k FWHM yielded ~38 scans/peak and <0.6 ppm error.
• Linearity and Precision: Calibration linearity (R2>0.99); repeatability RSD <10% for 10 µg/kg in all matrices, well under 20% threshold.
• Robustness: 100 consecutive injections of tomato extract over 66 hours showed stable sensitivity (RSD 3.8–5.3%) and mass accuracy ≤1 ppm without maintenance.
• Scope: 99.3% of pesticide/matrix combinations quantifiable below MRL with regulatory compliance.

Benefits and Practical Applications

• Wide‐scope full‐scan acquisition removes need for compound‐specific SIM or SRM methods.
• High resolving power enhances selectivity and confidence in complex matrices.
• Automated data processing accelerates routine analyses and reporting.
• Robust long‐term performance supports high‐throughput testing labs.

Future Trends and Potential Applications

Continued advances in high‐resolution MS will extend scope to emerging contaminants and multimode matrices. Integration with data‐driven software and spectral libraries will further streamline workflows. Potential exists for on‐site or field‐deployable high‐res instruments and cloud‐based analytics to enable real‐time monitoring.

Conclusion

The Thermo Scientific Exactive GC Orbitrap MS method fulfills SANTE/11945/2015 requirements for routine pesticide residue analysis. It delivers low detection limits, sub‐ppm mass accuracy, excellent precision and long‐term stability, making it a robust solution for regulatory and industrial laboratories.

Reference

1. SANTE/11945/2015 Guidance document on analytical quality control and method validation procedures for pesticide residues analysis in food and feed.
2. Belmonte Valles N., Retamal M., Martinez‐Uroz M.A., Mezcua M., Fernandez‐Alba A.R., de Kok A. (2012) Determination of chlorothalonil in difficult‐to‐analyse vegetable matrices using multiresidue methods. Analyst 137(10):2513–2520.