Evaluation of the Performance of an LC-MS/MS Method for the Determination of Anionic Polar Pesticide Residues in Crops and Foodstuffs Using an Interlaboratory Study

Significance of the Topic

Polar anionic pesticides such as glyphosate and its metabolites pose analytical challenges due to their high polarity and significant matrix effects. Accurate quantification in foodstuffs is critical for regulatory compliance, consumer safety, and trade.

Objectives and Study Overview

This interlaboratory study evaluated a method combining Quick Polar Pesticides (QuPPe) extraction with LC-MS/MS separation on an Anionic Polar Pesticide column. Eight laboratories across Europe and India assessed accuracy, repeatability, and reproducibility using spiked cucumber extracts.

Methodology and Instrumentation

• Extraction: QuPPe acidified methanol extraction of cucumber matrix without cleanup.
• Analytes: Glyphosate, AMPA, glufosinate, MPPA, ethephon spiked at 0.02–0.05 mg/kg.
• Internal standards: Stable isotope analogues (except for ethephon).
• Instrumentation: Waters ACQUITY UPLC I-Class PLUS with Xevo TQ-XS triple quadrupole MS; Anionic Polar Pesticide column (2.1×100 mm, 5 µm).
• Calibration: Matrix-matched standards from 0.005 to 0.2 mg/kg, linear fit with 1/x weighting.

Main Results and Discussion

• Chromatography: Gaussian peak shapes, retention times within 3% of reference; stability over 15 injections.
• Retention precision: RSDr <0.15% (within lab), RSDRL <2.5% (between labs).
• Linearity: r² >0.99, residuals <20% (high-concentration outliers excluded).
• Accuracy: Trueness between 90% and 104%, bias <10% relative to reference values.
• Precision: Repeatability and reproducibility RSD <7% for all analytes.
• Identification challenge: Ethephon qualifier ion exhibited elevated background, limiting confirmatory detection at low levels.

Benefits and Practical Applications

• Proven across multiple sites, boosting confidence for routine monitoring of polar anionic pesticides.
• Minimal sample preparation suits high-throughput official control and due diligence testing.
• Comprehensive start-up guides and support ensure global implementation and method transferability.

Future Trends and Potential Applications

• Extension to other highly polar agrochemicals and diverse food matrices.
• Integration with high-resolution MS for increased specificity and screening scope.
• Automation of QuPPe workflows to enhance throughput and consistency.

Conclusion

The interlaboratory evaluation confirms that the QuPPe-based LC-MS/MS method with an Anionic Polar Pesticide column delivers robust, accurate, and precise quantification of key anionic polar pesticide residues in cucumber. Compliance with SANTE guidelines and ease of setup support widespread adoption in regulatory and industrial laboratories.

References

1. Anastassiades M. et al. Quick Method for the Analysis of Numerous Highly Polar Pesticides in Food (QuPPe-PO-Method v11), 2020.
2. Ross E. et al. Determination of Anionic Polar Pesticides in High Water Foodstuffs. Waters Application Note 720006645EN, 2018.
3. Waters Anionic Polar Pesticide Column Care and Use Manual, 720006666EN.
4. Waters Method Startup Guide for Anionic Polar Pesticide Column, 720006689EN.
5. SANTE/12682/2019. Guidance Document on Analytical Quality Control and Method Validation for Pesticide Residues in Food and Feed.