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

Significance of the topic

Edible oils contain high lipid loads that interfere with GC-MS/MS analysis and can lead to frequent maintenance and poor chromatographic performance; developing efficient cleanup protocols is essential for accurate pesticide residue determination.

Objectives and Study Overview

This study sought to establish a streamlined, low-solvent method for quantifying 150 pesticides in olive oil, replacing conventional hexane/GPC workflows with acetonitrile extraction and SPE or freeze-out cleanup, and to assess calibration approaches recommended by EU SANTE guidelines.

Methodology and Instrumentation

• Sample preparation: retail-sourced olive oil samples inverted and spiked with a mixture of 150 pesticide standards.
• Extraction strategy: acetonitrile-based extraction to avoid hexane; two cleanup paths evaluated:
  1. Method 1: direct pass-through SPE using Oasis PRiME HLB cartridges.
  2. Method 2: lipid precipitation by freezing followed by SPE pass-through.
• Calibration: comparison of matrix-matched curves with procedural standard calibration (spiking blank oil before extraction to correct for matrix effects and low recoveries).
• Instrumentation: Waters Xevo TQ-GC system (GC-EI-MS/MS) employing multiple reaction monitoring and triphenyl phosphate as internal standard; detection limits down to 0.005 mg/kg.

Main Results and Discussion

Acetonitrile extraction combined with SPE cleanup achieved overall recoveries above 70% for the majority of analytes. Replacement of hexane defatting with a freeze-out step notably enhanced organochlorine recoveries (e.g., aldrin, hexachlorobenzene). SPE pass-through on Oasis PRiME HLB exhibited minimal retention of target compounds. Procedural standard calibration improved trueness to 99–108% and maintained excellent linearity (R² > 0.995) across 0.005–0.1 mg/kg.

Benefits and Practical Applications

• Significant reduction in solvent usage and preparation time compared to traditional hexane/GPC methods.
• High sensitivity and reproducibility for routine multi-residue screening in fatty matrices.
• Simplified SPE pass-through extends instrument maintenance intervals by minimizing lipid introduction.

Future Trends and Applications

Further adoption of procedural standard calibration for complex food matrices, exploration of advanced SPE sorbents for enhanced selectivity, and integration with high-resolution mass spectrometry are anticipated to broaden the applicability of this approach to diverse edible oils and other lipid-rich commodities.

Conclusion

The combined acetonitrile extraction, freeze-out defatting, and Oasis PRiME HLB SPE cleanup, paired with procedural standard calibration on the Xevo TQ-GC platform, delivers a greener, efficient, and robust solution for routine pesticide residue analysis in edible oils.

References

• European Union. SANTE/11813/2017. Guidance Document on Analytical Quality Control and Method Validation Procedures for Pesticides Residues Analysis in Food and Feed.