Validation Results for LC/MS/MS Pesticide Multiresidue Analysis Using Triggered MRM and Online Dilution

Significance of the Topic

This study addresses the need for robust, high-throughput multiresidue screening of over 500 pesticides in complex food matrices using an advanced LC/MS/MS workflow. Ensuring accurate detection and quantification of trace pesticide residues is critical for food safety monitoring, regulatory compliance, and consumer protection.

Objectives and Study Overview

The main goal was to validate an improved Agilent LC/MS/MS pesticide multiresidue method incorporating triggered multiple reaction monitoring (MRM) and online dilution. Key objectives included:

• Assessing trueness (recovery) and precision (repeatability and intermediate precision) across tomato, orange juice, spinach, and wheat flour.
• Verifying compliance with European Commission SANTE/11945/2015 guidelines.
• Estimating measurement uncertainty for routine result interpretation.

Methodology and Instrumentation

Sample Preparation:

• QuEChERS extraction with acetonitrile partitioning and cleanup steps tailored to each matrix.
• Fortification at 0.01 and 0.02 mg/kg, with five replicates per level.

Instrumental Analysis:

• Agilent LC/MS/MS system configured for triggered MRM to extend dynamic range and improve sensitivity.
• Online dilution to accommodate high-concentration samples without manual reanalysis.

Quantification and Quality Control:

• Use of matrix-matched calibration and standard addition for challenging analytes.
• Intermediate precision evaluated by a second analyst on a different day.
• Measurement uncertainty estimated at 95 % confidence, with expanded MU ≤ 50 % applied per SANTE guidance.

Results and Discussion

General Performance:

• Mean recoveries for most pesticides fell within 70–120 %, with RSD ≤ 20 % in all matrices.
• Expanded MU values were below 50 % in the majority of cases, supporting reliable quantification.

Matrix-Specific Observations:

• Tomato and orange juice: high recoveries and low RSDs for the bulk of analytes.
• Spinach: several polar or labile pesticides (e.g., alanycarb, benfuracarb, carbosulfan) showed lower recoveries due to matrix-induced degradation.
• Wheat flour: certain pesticides (e.g., diuron, azoxystrobin) displayed variable recoveries, highlighting the benefit of online dilution.

Analyte-Specific Notes:

• Quinmerac and tribenuron-methyl exhibited sub-optimal recoveries in most matrices due to high polarity.
• Spinosad (spinosyns A and D) showed greater variability in leafy matrices.
• Several GC-amenable analytes (e.g., bifenthrin, dichlorvos, disulfoton) were retained for confirmatory LC/MS/MS results when sensitivity allowed.

Benefits and Practical Applications

This validated workflow offers:

• Comprehensive coverage of hundreds of pesticides in diverse food commodities.
• High throughput with online dilution and triggered MRM reducing manual interventions.
• Regulatory compliance with EU SANTE guidelines, providing defensible data for food safety authorities and quality control laboratories.

Future Trends and Utilization Opportunities

Emerging directions include:

• Integration of data-independent acquisition (DIA) to complement targeted MRM for non-target screening.
• Automation of sample prep and improved miniaturized extraction to boost throughput and reduce solvent use.
• Application to environmental and biological monitoring for broader pesticide exposure assessment.

Conclusion

The improved Agilent LC/MS/MS pesticide multiresidue method with triggered MRM and online dilution demonstrates reliable trueness, precision, and measurement uncertainty across multiple food matrices. Compliance with SANTE/11945/2015 ensures its suitability for routine regulatory and quality control applications.

Reference

• European Commission SANTE/11945/2015 Guidance Document on Quality Control and Method Validation for Pesticide Residue Analysis in Food and Feed
• Agilent Application Note 5991-7193EN: Improved LC/MS/MS Pesticide Multiresidue Analysis Using Triggered MRM and Online Dilution