Fast Analysis of Multi-Class Pesticides Panel in Garlic and Cumin Extracts Using a Single Run LC-High Resolution Mass Spectrometry

Significance of the Topic

Multi-class pesticide residue analysis in spices such as garlic and cumin is essential for ensuring food safety and regulatory compliance. Trace levels of diverse pesticides pose health risks, and rapid, reliable methods are needed to monitor them at or below European maximum residue limits.

Goals and Overview of the Study

This study presents a streamlined workflow for the simultaneous quantitative determination and unknown screening of over 700 pesticide residues in garlic and cumin extracts. It aims to combine a single-run liquid chromatography–high-resolution accurate mass spectrometry (LC-HRAM) method with advanced data acquisition features, delivering sensitivity, precision, and ease of use for routine food safety laboratories.

Instrumentation

• Thermo Scientific™ Vanquish™ Flex Binary UHPLC system
• Thermo Scientific™ Orbitrap Exploris™ 120 mass spectrometer
• Thermo Scientific™ TraceFinder™ software for automated data processing

Methodology and Instrumentation

Sample preparation employed a modified QuEChERS protocol: 2 g of spice powder spiked with pesticide standards, extraction with acetonitrile/water and QuEChERS salts, followed by filtration. Chromatographic separation used a C18-based Accucore aQ column (2.1 × 100 mm, 2.6 μm) at 25 °C with a 15-minute water/methanol gradient containing 5 mM ammonium formate and 0.1 % formic acid. The Orbitrap Exploris 120 operated in positive mode at 60 000 resolution for full scan and 15 000 for data-independent acquisition (DIA) or AcquireX workflows. AcquireX generated exclusion lists from blank matrices to focus MS2 scans on relevant ions. Data processing and reporting were automated via TraceFinder.

Main Results and Discussion

Calibration curves in matrix-matched standards ranged from 0.5 to 100 ppb, with over 95 % of compounds exhibiting r2 > 0.99. Limits of quantitation (LOQs) as low as 0.5 ppb were achieved for both garlic and cumin, compliant with EU SANTE guidance. Recoveries at three concentration levels (1.3, 6.6, 13.3 μg/kg) fell between 70 % and 120 % with relative standard deviations under 15 %. Spectral library matching and fragment confirmation met mass accuracy (≤5 ppm) and retention time (±0.1 min) criteria. The AcquireX workflow enhanced the identification of unknown contaminants, demonstrated by the detection of proxan, a non-steroidal anti-inflammatory drug, in garlic extracts.

Benefits and Practical Applications of the Method

• Rapid single-run analysis reduces instrument time to 15 minutes per sample.
• High sensitivity and accuracy meet stringent regulatory requirements for a broad pesticide panel.
• Automated data processing streamlines targeted quantitation and unknown screening.
• AcquireX reduces false positives/negatives by excluding background matrix ions and reallocating MS2 scans.

Future Trends and Applications

Continued development will expand the compound database and apply the workflow to additional complex food matrices. Identification of unknowns will benefit from complementary techniques such as NMR or chemical synthesis. Integration with high-throughput sample handling and enhanced software algorithms will further improve screening capabilities and laboratory efficiency.

Conclusion

The presented LC-HRAM workflow offers a robust, rapid, and sensitive approach for multi-class pesticide analysis in spices, fulfilling EU regulatory standards. Its combination of QuEChERS sample preparation, high-resolution mass spectrometry, and intelligent data acquisition provides a turnkey solution for both targeted quantitation and unknown contaminant screening. Ongoing efforts will focus on expanding compound coverage and refining unknown identification strategies.

Reference

European Commission. SANTE/12682/2019 Guidelines on Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis.