Analysis of 510 Pesticide Residues in Honey and Onion on an Agilent 6470 Triple Quadrupole LC/MS System

Importance of the topic

Monitoring pesticide residues in food is essential to protect consumer health and comply with international regulatory standards. Honey and onion pose distinct analytical challenges due to their high sugar and high water content, respectively, which can cause matrix effects in LC/MS analyses. Reliable methods support routine screening and ensure that products meet maximum residue limits (MRLs) set by agencies such as WHO, EU, and EPA.

Objectives and Study Overview

This work extends an Agilent LC/MS/MS workflow covering 510 pesticide targets to honey and onion matrices. Key goals included optimizing sample preparation, evaluating matrix effects, and verifying method performance against SANTE/12682/2019 guidelines. The study assesses sensitivity, quantitation limits, calibration linearity, recovery, and precision across intra- and interlaboratory conditions.

Methodology

Sample extraction employed a QuEChERS EN protocol followed by dispersive SPE cleanup. Honey (5 g) was diluted with water and acetonitrile, and onion (10 g) was homogenized before extraction. Matrix-matched calibration standards (1–100 µg/L) were prepared by post-spiking blank extracts. Dynamic MRM acquisition captured two to three transitions per pesticide. Data processing used Agilent MassHunter software.

Used Instrumentation

• Agilent 1290 Infinity II LC system with ZORBAX RRHD Eclipse Plus C18 column (2.1×150 mm, 1.8 µm)
• Agilent 6470 triple quadrupole mass spectrometer with Jet Stream electrospray source
• Agilent BondElut QuEChERS EN extraction and dispersive SPE kits
• Geno/Grinder homogenizer, centrifuges, vortex mixers

Main Results and Discussion

The method achieved sub-10 ng/mL detection limits for 99% of targets and LOQs at or below 10 µg/kg (85% ≤1 µg/kg). Over 95% of pesticides showed calibration linearity (R² ≥0.99). Matrix effects varied: ~15% of honey and ~70% of onion targets exhibited significant ion suppression or enhancement, underscoring the need for matrix-matched calibration. Recovery studies at 10 µg/kg yielded 40–120% recovery for 88% of honey and 93% of onion targets (RSDr ≤20%). Intra- and interlaboratory precision (RSDr and RSDiR) met ≤20% for >90% of compounds. Retention time shifts remained within ±0.1 min. Robustness testing over 15 injections across three days produced RSD <4% for representative pesticides.

Benefits and Practical Applications

This validated workflow delivers high throughput and reliable quantitation of over 500 pesticide residues in diverse food matrices. It is transferable across laboratories and analysts, supporting routine QA/QC and compliance testing in food safety and environmental monitoring laboratories.

Future Trends and Applications

Further enhancements may include migration to ultra-sensitive platforms (e.g., Agilent 6495), implementation of online dilution or triggered MRM strategies, and expansion to more complex or emerging matrices. Advances in automated data processing and non-target screening will broaden screening capabilities and improve laboratory efficiency.

Conclusion

An optimized QuEChERS-based LC/MS/MS workflow on the Agilent 6470 system provides robust, sensitive, and precise analysis of 510 pesticide residues in honey and onion. Method performance complies with SANTE guidelines, enabling reliable routine monitoring and regulatory compliance.

References

1. Zou A. et al. Comprehensive LC/MS/MS Workflow of Pesticide Residues in Food Using the Agilent 6470 Triple Quadrupole LC/MS System. Agilent Technologies application note 5994-2370EN, 2020.
2. European Commission. SANTE/12682/2019: Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed. 2019.
3. Quantitative Analysis of Multiresidue Pesticides in Food Matrices Using Agilent 6470 Triple Quadrupole LC/MS System – Method Protocol. Agilent Technologies, 2021.
4. C hemical Standards. Agilent Technologies, www.agilent.com/chem/standards Accessed May 2021.
5. Mastovska K. Improved LC/MS/MS Pesticide Multiresidue Analysis Using Triggered MRM and Online Dilution. Agilent Technologies application note 5991-7193EN, 2017.