Multiresidue Method for the Quantification of Pesticides in Fruits, Vegetables, Cereals and Black Tea using UPLC-MS/MS

Significance of the Topic

Growing global demand for food and stringent regulatory limits for pesticide residues require sensitive, high-throughput analytical methods. Multi-residue analysis enables simultaneous detection of hundreds of pesticides in diverse commodities, ensuring compliance with Maximum Residue Levels and safeguarding consumer health.

Goals and Study Overview

The study aimed to develop a single UPLC-MS/MS workflow to quantify 552 pesticides and relevant metabolites in fruits, vegetables, cereals and black tea. Representative matrices with varying composition—high-water (spinach), high-acid/high-water (strawberry), high-oil/low-water (soybean), high-protein/low-water (wheat flour), and complex tea—were selected to evaluate method robustness.

Methodology

Sample preparation used QuEChERS CEN protocols adapted for each matrix:

• High-water and acidic fruits/vegetables: 10 g sample, acetonitrile extraction, salt mixture, centrifugation
• Cereals and low-water commodities: 5 g sample with water and acetonitrile, QuEChERS salts, freezing step for soybean and wheat flour
• Black tea: 2 g sample, water soak, acetonitrile extraction, dispersive SPE cleanup

Calibration standards were matrix-matched over 0.0001–0.1 mg/kg to mimic regulatory MRL ranges.

Instrumentation

The method utilized:

• ACQUITY UPLC I-Class with FL Sample Manager and HSS T3 column (2.1×100 mm, 1.8 μm)
• Xevo TQ-XS triple quadrupole mass spectrometer in electrospray positive and negative modes
• MassLynx and TargetLynx software with Quanpedia database for automated LC and MS method generation
• Post-injector mixing kit to enhance peak shape of early eluting polar analytes

Key Results and Discussion

Chromatographic performance:

• Polar pesticides yielded sharp, symmetric peaks (<7 s width) when using the post-injector mixing kit to improve aqueous dispersion
• Retention times were stable (±0.1 min) and well separated from void volume

Quantitative figures:

• Calibration curves for 256 test compounds achieved r2>0.99 with back-calculated concentrations within ±20%
• Over 85% of pesticides exhibited peak area RSDs below 10% across replicate injections

Matrix effects varied by commodity, with both suppression and enhancement observed; matrix-matched calibration and sample dilution (up to 10×) effectively mitigated interferences while preserving detection limits.

Benefits and Practical Applications

This unified workflow delivers rapid (<19 min runtime), robust quantitation of a broad pesticide panel at levels below EU default MRLs. High throughput, minimal maintenance, and database-driven method updates support applications in routine food monitoring, quality control, and regulatory compliance.

Future Trends and Opportunities

Continued expansion of compound libraries, integration with high-resolution mass spectrometry, and AI-assisted data processing will enhance selectivity and throughput. Miniaturized and green sample preparation techniques, together with cloud-based analytics, promise decentralized, on-site multi-residue screening capabilities.

Conclusion

The developed UPLC-MS/MS approach combining QuEChERS extraction, post-injector mixing and comprehensive spectral editing provides a powerful tool for trace-level pesticide monitoring across diverse food matrices, ensuring food safety and regulatory adherence.

References

1. EURL-FV Multiresidue Method using QuEChERS followed by GC-QqQ/MS/MS and LC-QqQ/MS/MS for Fruits and Vegetables, European Union Reference Laboratory
2. Determination of pesticide residues in cereals and feeding stuff by LC-MS/MS and GC-MS/MS (QuEChERS method), European Union Reference Laboratory
3. Multi-Residue Pesticide Analysis in Tea: Optimized Cleanup After QuEChERS Extraction for UPLC-MS/MS and GC-MS/MS Analysis, Waters Corporation
4. European Commission SANTE/12682/2019: Analytical quality control and method validation procedures for pesticide residues analysis in food and feed