EVALUATING SYSTEM PERFORMANCE DURING ROUTINE ANALYSIS OF FOOD COMMODITIES FOR PESTICIDE RESIDUES

Significance of the Topic

The routine monitoring of pesticide residues in food commodities is critical for ensuring consumer safety and regulatory compliance. Variations in physicochemical properties across analytes and complex food matrices create analytical challenges that can impact accuracy, throughput and instrument reliability.

Objectives and Study Overview

This study aimed to assess the performance of a multi-residue LC-MS/MS workflow for 552 pesticides and metabolites, focusing on 256 target analytes in accordance with EU Regulation 2019/533/EU. Representative samples were selected from five diverse commodity groups (spinach, strawberry, soybean, wheat flour and black tea) to evaluate method robustness under routine conditions.

Methodology and Instrumentation

Samples were processed by the QuEChERS CEN protocol, diluted and analyzed by LC-MS/MS. Key instrumentation included:

• LC system: ACQUITY UPLC I-Class PLUS with FL SM
• Column: ACQUITY HSS T3 2.1 x 100 mm
• Injection: 5 μL with post-injector mixing kit (50 μL extension loop)
• MS: Xevo TQ-XS triple quadrupole with electrospray ionisation (positive/negative switching)
• Acquisition: Time-windowed MRM (≥2 transitions per analyte)

Matrix-matched calibration curves (0.0001–0.1 mg/kg) bracketed replicate spikes at 0.005, 0.01 and 0.05 mg/kg without internal standards.

Main Results and Discussion

The method delivered excellent retention time stability and peak shapes for early eluting polar compounds across all matrices. Calibration linearity was high (R2 > 0.99), and >80% of analytes exhibited RSDs below 10% at 0.005 mg/kg. Matrix effects were characterized by comparing crude and diluted QuEChERS extracts; a 5–10× dilution combined with matrix-matched calibration effectively mitigated signal suppression or enhancement. Continuous QC injections before and after each batch demonstrated consistent instrument performance over three days without intervention.

Benefits and Practical Applications

• Comprehensive coverage of regulatory-relevant pesticides across diverse food types
• High sensitivity down to 0.005 mg/kg for most compounds
• Reduced instrument maintenance through extract dilution
• Alignment with SANTE/12682/2019 guidelines for routine laboratory use

Future Trends and Potential Applications

Advances may include integration of high-resolution mass spectrometry for enhanced selectivity, automated data processing and digital quality control workflows. Extending the scope to emerging contaminants and applying predictive algorithms for matrix effect correction will further streamline routine analyses.

Conclusion

The developed multi-residue LC-MS/MS method offers robust, sensitive and high-throughput performance for routine pesticide residue monitoring in food commodities, meeting stringent EU regulatory requirements while minimizing maintenance demands.

References

• Commission Implementing Regulation 2019/533/EU
• SANTE/12682/2019: Guidance on analytical quality control and method validation
• EURL-FV Multiresidue Method using QuEChERS followed by GC-QqQ/MS/MS and LC-QqQ/MS/MS for Fruits and Vegetables
• EURL for cereals and feeding stuff: Determination of pesticide residues by LC-MS/MS and GC-MS/MS
• Multi-Residue Pesticide Analysis in Tea: Optimized Cleanup after QuEChERS Extraction for UPLC-MS/MS and GC-MS/MS