DETERMINATION OF PESTICIDES IN EDIBLE OILS BY GC-MS/MS

Importance of the Topic

Determination of pesticide residues in edible oils is critical due to regulatory limits and the complex lipid-rich matrix that challenges sample preparation and chromatographic performance. A robust, efficient approach helps ensure consumer safety, reduces instrument downtime and aligns with green chemistry principles.

Objectives and Study Overview

This study evaluated two streamlined workflows for extraction and cleanup of 150 target pesticides in olive oil. It compared a traditional hexane-based liquid-liquid extraction and GPC cleanup with simplified acetonitrile extraction coupled to either SPE pass-through or a freeze-out defatting step. A procedural-standards calibration strategy was also assessed to address low analyte recoveries and matrix effects.

Methodology and Instrumentation

Samples from retail olive oils were spiked with a pesticide mix prior to extraction. Method 1 replaced GPC with an Oasis PRiME HLB SPE pass-through cleanup following acetonitrile extraction. Method 2 further reduced nonpolar solvent use by introducing a freeze-out step for lipid precipitation before SPE. All extracts were analyzed by GC-EI-MS/MS on a Xevo TQ-GC system, using triphenylphosphate as internal standard.

Main Results and Discussion

• Extraction recoveries exceeded 70% for most pesticides using acetonitrile and SPE, outperforming hexane-GPC for organochlorines.
• Freeze-out defatting significantly improved recoveries of challenging analytes (e.g., aldrin, hexachlorobenzene).
• SPE pass-through cleanup did not retain analytes, ensuring minimal losses.
• Procedural-standards calibration delivered trueness of 99–108% and excellent linearity (R² > 0.995) across 0.005–0.1 mg/kg.
• Limits of quantitation as low as 0.005 mg/kg were achieved for the most demanding compounds.

Benefits and Practical Applications

• Reduced solvent consumption and shorter preparation times increase laboratory throughput and sustainability.
• Simplified cleanup minimizes instrument contamination and maintenance.
• Procedural-standards calibration enhances accuracy in complex matrices without improving extraction efficiency.
• Validated approach supports routine multi-residue monitoring in compliance with regulatory guidelines.

Used Instrumentation

• Xevo TQ-GC system for GC-EI-MS/MS analysis
• Oasis PRiME HLB SPE cartridges for pass-through cleanup

Future Trends and Potential Applications

• Integration of high-resolution mass spectrometry for broader analyte scope and non-target screening.
• Automation of freeze-out and SPE steps for high-throughput laboratories.
• Extension of procedural-standards calibration to other complex food matrices (e.g., fatty fish, dairy).
• Development of miniaturized extraction formats to further reduce solvent use and waste.

Conclusion

The simplified acetonitrile extraction with freeze-out defatting and SPE cleanup provides a greener, efficient and reliable method for multi-residue pesticide analysis in edible oils. Coupled with GC-EI-MS/MS and procedural-standards calibration, the workflow meets stringent recovery, sensitivity and repeatability requirements for routine compliance testing.

Reference

1. European Union (2017), Document No. SANTE 11813/2017. Guidance Document on Analytical Quality Control and Method Validation Procedures for Pesticides Residues Analysis in Food and Feed.