Development of a high-resolution MRM quantitative method for pesticides in apple, honey, olive oil, orange and tomato food matrices

Importance of the Topic

Multi-residue pesticide screening in food matrices is critical for consumer safety and regulatory compliance. High-resolution quantitative methods enable detection of trace-level contaminants across diverse commodities, supporting public health and meeting stringent maximum residue limits (MRLs) set by global agencies.

Objectives and Study Overview

This work aimed to develop and validate a high-resolution multiple reaction monitoring (MRM) LC–MS/MS method on a QTOF platform for over 300 pesticides. The method was benchmarked against a data-independent acquisition (DIA) approach, with performance assessed in apple, honey, olive oil, orange and tomato matrices at target concentration levels as low as 0.1 µg/kg.

Methodology and Instrumentation

Sample Preparation and Extraction:

• 317 pesticides plus 10 deuterated internal standards spiked into five food matrices (0.1–100 µg/kg).
• Standard QuEChERS extraction followed by cleanup steps.

Chromatography and Mass Spectrometry:

• Reverse-phase LC on Shim-pack Velox Biphenyl column (100 × 2.1 mm, 2.7 µm) at 45 °C.
• Shimadzu LCMS-9050 QTOF operated in positive ESI mode; external mass calibration with continuous calibrant infusion.
• High-resolution scanning MRM: targeted TOF MS scan (m/z 110–950) plus MS/MS scans with optimized collision energies transferred from a triple quadrupole library.
• DIA-MS/MS comparison: wider precursor isolation windows (20–35 Da) and collision energy ramps.

Main Results and Discussion

Signal Intensity and Sensitivity:

• High-resolution MRM yielded reference ion signals up to threefold greater than DIA, enabling limits of quantitation below 1 µg/kg.
• Narrow isolation windows (0.8 Da) and specific collision energies enhanced selectivity for co-eluting analytes.

Repeatability and Regulatory Compliance:

• %RSD ≤ 20% (n = 6) for 312 out of 317 targets at the 10 µg/kg MRL in tomato matrix.
• All analytes met EU SANTE 11312/2021 v2 reporting criteria for quantitation and mass accuracy.

Comparison with DIA:

• DIA provided broader coverage but at the expense of sensitivity and selectivity.
• High-resolution MRM demonstrated lower mass error (< 5 ppm) and improved peak area ratios for key pesticides.

Benefits and Practical Applications

This targeted high-resolution MRM approach offers:

1. Enhanced detection capability for regulatory monitoring and food safety laboratories.
2. Versatility across complex matrices including high-fat and high-sugar commodities.
3. Streamlined adoption by labs already using triple quadrupole methods due to matched collision energies.

Future Trends and Potential Applications

Emerging opportunities include:

• Integration of automated data processing and AI-driven method optimization.
• Expansion of high-resolution MRM libraries to cover novel or emerging contaminants.
• Coupling with ion mobility separation for additional selectivity in complex matrices.
• Application to other commodity types and environmental samples.

Conclusion

The high-resolution scanning MRM method on a QTOF platform delivers superior sensitivity and selectivity for multi-residue pesticide quantitation compared to DIA-MS/MS. It meets EU SANTE guidelines, exhibits robust repeatability, and supports lower limits of quantification, making it a powerful tool for routine food safety analysis.

References

• European Commission. SANTE/11312/2021 v2 – Guidance on analytical quality control and method validation for pesticide residues in food and feed.