A multiresidue method for pesticide profiling using an Orbitrap Tribrid mass spectrometer

Significance of the topic

Pesticide residues in food pose health risks and are regulated by maximum residue levels (MRLs) globally. Rapid, high-confidence screening of hundreds of compounds in complex matrices demands advanced analytical workflows. High-resolution accurate-mass (HRAM) full-scan LC-MS combined with automated data-dependent acquisition enhances detection of both known and unexpected pesticides, supporting food safety and regulatory compliance.

Objectives and overview

This study presents a multiresidue method using the Thermo Scientific™ Orbitrap ID-X™ Tribrid™ mass spectrometer and the AcquireX™ intelligent workflow. Goals include simultaneous targeted quantitation and post-acquisition non-targeted screening of ~250 pesticides spiked into strawberry matrix across a wide concentration range, from sub-ppb levels to hundreds of ppb, while ensuring robustness, reproducibility, and ease of use.

Methodology and instrumentation

Sample Preparation:

• Strawberries homogenized by IKA ULTRA-TURRAX.
• QuEChERS extraction with MgSO₄, trisodium citrate buffer, and acetonitrile.
• Matrix-matched standards prepared at 0.05–200 ng/mL.

Chromatography:

• Vanquish™ Flex UHPLC, Accucore™ aQ C18 (100×2.1 mm, 2.6 µm).
• Mobile phases A/B: water/methanol (98:2) and methanol/water (98:2), both with 5 mM ammonium formate, 0.1% formic acid.
• Flow: 300 µL/min, 25 °C, 15 min runtime.

Mass Spectrometry:

• Orbitrap ID-X Tribrid with AcquireX™ workflow.
• Full-scan HRAM MS at 60,000 resolving power (@ m/z 200), AGC target 2e5.
• Top-7 DDA MS/MS with dynamic exclusion, HCD at stepped energies 20/40/70%, 15,000 resolution, AGC 5e4.

Data Processing:

• TraceFinder™ for quantitation (±5 ppm mass tolerance, S/N ≥3 for LOD, ≥10 for LOQ).
• Compound Discoverer™ with mzCloud spectral library for MS/MS matching and identification points evaluation.

Main results and discussion

• Quantitation and detection:

• All 250 pesticides detected at 10 ppb; 96% detected 100-fold lower.
• 94% of compounds achieved LOQs of 0.5 ppb with %RSD and %CV <8%.

• MS/MS identification:

• High-confidence spectral matches (Pearson dot-product >0.9) at sub-ppb levels for representative compounds.
• Average of 6–7 DDA cycles per peak despite 6 s peak widths, enabling multiple identification points per analyte.

• AcquireX vs. standard DDA:

• AcquireX yielded ~92% interrogation of spiked pesticides at ≤10 ppb compared to ~65% with standard DDA/DE.
• Reproducible performance on successive days with <2% variation in number of identified compounds.

Benefits and practical applications

This workflow simplifies method development by automating background exclusion, maximizes instrument cycle time for compounds of interest, and supports retrospective data mining. High resolution and mass accuracy reduce false positives, while full-scan acquisition enables simultaneous targeted quantitation and non-targeted screening. Applicable across diverse food matrices, it enhances laboratory throughput and regulatory compliance.

Future trends and potential applications

• Expansion of HRAM spectral libraries and suspect screening databases.
• Integration with machine learning for real-time feature prioritization.
• Application to environmental, clinical, and forensic residue analysis.
• Development of continuous acquisition strategies for ultra-low-level monitoring.

Conclusion

The Orbitrap ID-X Tribrid mass spectrometer combined with the AcquireX workflow offers a powerful, robust multiresidue pesticide profiling platform. It delivers high sensitivity, broad dynamic range, and reliable identification of both known and unexpected compounds, supporting stringent food safety regulations and enabling comprehensive residue surveillance.

References

1. del Mar Gomez-Ramos MR et al. Anal Bioanal Chem. 2015;407:6317–6326.
2. Wong J et al. J Agric Food Chem. 2010;58:5897–5903.
3. Niessen WM. Mass Spectrom Rev. 2006;25:881–899.
4. Ferrer I et al. J Chromatogr A. 2005;1082:81–90.
5. Barbieri M et al. Sci Total Environ. 2019;653:958–967.
6. Martinez-Dominguez GR-G et al. Food Chem. 2016;197:907–915.
7. Kalli AS. J Am Soc Mass Spectrom. 2019;30:1147–1155.
8. Shi F et al. J Chromatogr A. 2014;1344:91–98.
9. Koplin DW et al. Environ Sci Technol. 2002;36:4007–4008.
10. Hernandez F. Anal Chem. 2004;76:4349–4357.