Multiresidue Analysis of Pesticides in Fruits and Vegetables Using UPLC-MS/MS

Significance of the Topic

Analysis of pesticide residues in fruits and vegetables is critical to ensure food safety and regulatory compliance. Multiresidue methods enable laboratories to monitor hundreds of compounds at trace levels, addressing global Maximum Residue Limits (MRLs).

Objectives and Study Overview

• Develop a validated multiresidue UPLC-MS/MS method for 190 pesticides.
• Assess performance in challenging matrices (white grapes and green beans) containing chlorophyll.
• Confirm compliance with EU SANTE/11945/2015 guidelines.

Instrumentation

• UPLC: ACQUITY UPLC H-Class with ACQUITY BEH C18 column (2.1×100 mm, 1.7 µm).
• MS/MS: Xevo TQ-S micro operating in ESI+ mode.
• Software and databases: MassLynx v4.1, TargetLynx XS, and Quanpedia pesticide method library.

Methodology

• Sample preparation: QuEChERS extraction using 15 g homogenate, 15 mL acetonitrile with 1% acetic acid, DisQuE AOAC dispersive SPE, and centrifugation.
• Calibration: Solvent and matrix-matched standards from 1 to 500 ppb (0.001–0.5 mg/kg).
• Chromatography: Gradient elution with 10 mM ammonium acetate (pH 5) in water and methanol, 0.45 mL/min flow, 45 °C column temperature, 10 µL injection.
• Detection: Two MRM transitions per analyte, AutoDwell to ensure ≥12 data points per peak.

Results and Discussion

• Linearity: 96% of pesticides achieved correlation coefficients (r) > 0.99 in both matrices.
• Recovery and precision: 96–97% of analytes showed recoveries within 70–120% at 0.01 mg/kg; most RSD values < 20%.
• Incurred residues: Identified carbendazim, propamocarb, pyrimethanil in green beans (< 0.07 mg/kg) and multiple fungicides/insecticides in grapes (< 0.25 mg/kg).
• Data processing: TargetLynx XS automatically verifies retention-time windows (± 0.1 min) and ion-ratio tolerances (< 30%).

Benefits and Practical Applications

• High-throughput screening of 190 pesticide residues in diverse produce.
• Compliance with EU MRLs and SANTE/11945/2015 validation criteria.
• Minimized false negatives via AutoDwell and comprehensive MRM monitoring.
• Scalable workflow allowing rapid inclusion of new analytes and reporting criteria.

Future Trends and Applications

• Incorporation of isotopically labeled internal standards to further improve precision.
• Expansion of compound libraries and automated acquisition windows.
• Integration of robotic sample preparation and real-time data analytics.
• Adoption of high-resolution accurate mass for untargeted screening alongside targeted MS/MS.

Conclusion

The presented UPLC-MS/MS approach delivers robust, sensitive, and high-throughput analysis of 190 pesticides in fruits and vegetables. It meets stringent regulatory requirements and offers a flexible platform for routine monitoring and method extension.

References

1. Waters Technology Brief No. 720004400en, Quanpedia Database: A Compendium for LC-MS/MS Method Development, 2012.
2. European Commission SANTE/11945/2015 Guidance on Analytical Quality Control and Method Validation for Pesticide Residues.