Determination of Multiclass, Multiresidue Pesticides in Olive Oils by Captiva EMR—Lipid Cleanup and GC/MS/MS

Significance of the Topic

Olive oil is a widely consumed edible oil with strict regulatory limits on pesticide residues due to potential health risks and the lipophilic nature of many pesticides. Accurate monitoring of multiclass pesticide residues at low concentration levels is essential for compliance with international maximum residue limits (MRLs) and for meeting consumer demand for high-quality and organic products. The complexity of the oil matrix poses analytical challenges, requiring efficient cleanup strategies to protect instrumentation and ensure reliable quantitation.

Objectives and Overview of the Study

This study aimed to develop and validate a robust multiresidue method for simultaneous determination of 26 representative pesticides in olive oil. The approach combined a two-step liquid–liquid extraction (LLE) with Agilent Captiva EMR—Lipid dispersive solid-phase cleanup and quantitation by gas chromatography coupled to triple quadrupole mass spectrometry (GC/MS/MS). Key goals included optimizing extraction efficiency for highly hydrophobic analytes, maximizing lipid removal to extend instrument uptime, and achieving regulatory-compliant recovery and precision across a broad calibration range.

Methodology

• Sample Preparation: 2.5 g olive oil was extracted twice with 5 mL of ethyl acetate/acetonitrile (20:80, v/v), vortexed 15 min and centrifuged.
• Cleanup: Combined supernatants were diluted with water and passed through a 6 mL Captiva EMR—Lipid cartridge by gravity. A secondary elution with 1.25 mL acetonitrile/water (80:20, v/v) improved recovery of highly lipophilic pesticides.
• Drying: Eluate was treated with 3.5 g anhydrous MgSO₄ to remove residual water, vortexed, centrifuged, and final extract transferred for GC/MS/MS analysis.

Instrumentation Used

• Gas Chromatograph: Agilent 7890B GC with multimode inlet (cold splitless injection, 2 µL) and dual HP-5ms UI columns (15 m × 0.25 mm, 0.25 µm).
• Mass Spectrometer: Agilent 7010A triple quadrupole operating in dynamic MRM mode (EI source at 280 °C).
• Software: Agilent MassHunter workstation for data acquisition and processing.
• Auxiliary Equipment: Centrifuge, vortex mixer, positive-pressure manifold, Captiva EMR—Lipid cartridges, MgSO₄ pouches.

Main Results and Discussion

• Extraction efficiency was enhanced by replacing conventional QuEChERS with two-step LLE in ethyl acetate/acetonitrile, achieving >60 % recoveries for all pesticides, including highly lipophilic organochlorines.
• Captiva EMR—Lipid cleanup removed 85 % of co-extracted matrix, outperforming PSA/C18 dSPE cleanup (55 % lipid removal), leading to cleaner extracts and extended instrument uptime.
• Method validation in olive oil demonstrated limits of quantitation as low as 1 ng/g for most analytes, calibration linearity (R² > 0.99) over 1–500 ng/g, and mean recoveries between 70 % and 120 % for 96 % of pesticides, with relative standard deviations below 20 %.
• Matrix-matched calibration and use of three deuterated/structural analog internal standards (atrazine-D5, DDT-D8, TPP) ensured consistent quantitation and control of matrix effects.

Benefits and Practical Applications

• High-throughput screening of multiple pesticide classes in edible oils with minimal method development.
• Substantial reduction in sample matrix load on GC/MS/MS systems, lowering maintenance frequency and extending column and inlet lifetimes.
• Compliance with stringent regulatory requirements and support for organic certification by achieving low ng/g quantitation limits.

Future Trends and Applications

Continued refinement of sorbent chemistries and integration with automated platforms may further streamline analysis of complex lipid-rich foods. Emerging high-resolution mass spectrometry and novel ionization techniques offer potential for non-targeted screening and broader pesticide surveillance. Adaptation of this workflow to other fatty matrices, such as animal fats and fish oils, will expand its applicability in food safety monitoring.

Conclusion

The combination of two-step LLE and Captiva EMR—Lipid cleanup with GC/MS/MS provides a simple, reliable, and sensitive multiresidue method for pesticide analysis in olive oil. The optimized protocol delivers high recoveries, excellent reproducibility, and significant matrix removal, meeting regulatory performance criteria and enhancing laboratory efficiency.

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