Pesticide residues screening and quantitation analysis in olive oil using an Orbitrap Exploris 240 HRMS

Significance of the topic

The monitoring of pesticide residues in edible oils is critical to ensure food safety and regulatory compliance. Olive oil, being a high-fat matrix, poses challenges for the detection of trace-level contaminants. High-resolution accurate-mass (HRAM) mass spectrometry coupled with efficient sample preparation techniques provides the sensitivity and selectivity required to detect multiple residues at or below legislated maximum residue levels (MRLs).

Goals and overview of the study

This work aimed to develop and validate a multi-residue screening and quantitation method for over 400 pesticides in olive oil. The objectives included:

• Achieving high-throughput analysis suitable for routine laboratories.
• Combining targeted quantitation and unknown contaminant screening in a single workflow.
• Meeting or exceeding regulatory requirements for sensitivity, selectivity, and quantitation accuracy.

Methodology

Olive oil samples were extracted using a modified QuEChERS protocol involving acetonitrile, water, and a standardized salt pack. Lipids were removed using a dedicated cartridge before UHPLC–HRMS analysis. Chromatographic separation employed a reversed-phase Accucore aQ column (100 × 2.1 mm, 2.6 µm) on a Vanquish Flex UHPLC system with a 15 min gradient from aqueous ammonium formate/formic acid to methanol-based mobile phase. Data were acquired in Full Scan-Data-Independent Acquisition (DIA) mode with stepped collision energies and polarity switching. The AcquireX background exclusion workflow prioritized analyte-specific MS2 events while minimizing background fragmentation.

Instrumentation

• Thermo Scientific Vanquish Flex Binary UHPLC system
• Thermo Scientific Accucore aQ reversed-phase column, 100 × 2.1 mm, 2.6 µm
• Orbitrap Exploris 240 mass spectrometer with HRAM capabilities
• Thermo Scientific TraceFinder software for automated data processing
• Thermo Scientific QuEChERS salt slim pack for extraction

Main results and discussion

The method demonstrated:

• Limits of quantitation (LOQs) of 0.5–10 ppb for most pesticides following SANTE guidelines.
• Calibration linearity with over 95 % of compounds showing r² > 0.95 across 0.5–500 ppb.
• Mass accuracy below 5 ppm for both precursor and fragment ions, retention time reproducibility within ±0.1 min after 250 injections.
• Robust column performance with consistent peak shape and sensitivity across hundreds of analyses.
• Successful library matching and fragment ion confirmation for targeted compounds, with spectral library scores above 60 %.
• Automated unknown screening identified matrix constituents such as fatty acids and unexpected contaminants (e.g., erucamide) via online and local database searches.

Benefits and practical applications

This integrated approach enables:

• Simultaneous targeted quantitation and non-targeted screening in a single run.
• Regulatory compliance at low part-per-billion levels in complex oil matrices.
• Retrospective data mining for new or unforeseen compounds using archived full-scan datasets.
• Streamlined workflows with automated software-driven compound identification and reporting.

Future trends and possibilities

Advancements may include:

• Expanding compound panels beyond 400 analytes for broader pesticide coverage.
• Enhanced spectral libraries and machine-learning algorithms for faster unknown identification.
• Integration of alternative extraction and cleanup strategies to further reduce matrix effects.
• Application of HRAM workflows to other challenging food matrices and environmental samples.

Conclusion

The presented QuEChERS–Orbitrap Exploris 240 HRMS method achieves sensitive, accurate, and robust multi-residue pesticide analysis in olive oil. It meets stringent regulatory criteria, supports high-throughput testing, and adds the capability for non-targeted screening of unknown contaminants, making it a versatile solution for modern food safety laboratories.

References

1. EU Reference Laboratories for Residues of Pesticides. Method Validation & Quality Control Procedures for Pesticide Residues Analysis in Food & Feed (SANTE/11813/2017).
2. U.S. FDA. Acceptance Criteria for Confirmation of Identity of Chemical Residues Using Exact Mass Data for the FDA FVM Program, September 2015.