Exploring the application of a universal method for pesticide screening in foods using a high data acquisition speed MS/MS

Significance of the Topic

Effective monitoring of pesticide residues in food is a critical aspect of ensuring consumer safety and environmental protection. Traditional targeted methods require individual optimization for each analyte, which is time-consuming and resource intensive. A universal screening approach using high-speed LC-MS/MS offers the potential to survey a wide pesticide panel in diverse food matrices with minimal method development.

Objectives and Study Overview

This study evaluated a single generic LC-MS/MS method for rapid screening of 172 pesticides (344 MRM transitions) in foods. By leveraging ultra-fast MRM acquisition and generic parameter settings, the authors aimed to achieve reliable detection at low parts-per-billion (ppb) levels without retention time scheduling.

Methodology

Sample preparation followed a modified QuEChERS-style protocol:

• Weigh 5 g of homogenized food sample.
• Add 20 mL water, stand 15 min; add 50 mL acetonitrile, homogenize.
• Partition 20 mL extract; add 10 g NaCl and 20 mL phosphate buffer (pH 7.0).
• Shake with anhydrous sodium sulfate, filter, concentrate.
• Purify via ENVI-Carb/LC-NH₂ SPE, elute with 25% toluene/acetonitrile, concentrate.
• Dissolve residue in methanol for LC/MS injection (4 mL final).

Chromatographic separation used a Shim-pack XR-ODSII column (75×2 mm, 2.2 µm) with a 20 min gradient of ammonium acetate in water and methanol at 0.2 mL/min and 40 °C.

Instrumentation Used

The analytical platform comprised:

• UHPLC: Shimadzu Nexera system.
• Mass spectrometer: Shimadzu LCMS-8040 triple quadrupole with ESI (±).
• Key features: 15 000 u/s scan speed, 555 MRM transitions/s, 5 ms dwell time, 1 ms pause, 15 ms polarity switching, and ~5× sensitivity improvement over earlier models.

Main Results and Discussion

Using a universal MRM method without retention time scheduling, the system screened 172 pesticides across leek, paprika, and green tea leaves. Ten pesticides spiked at 10 ppb were automatically identified in each matrix. False positive rates out of 172 analytes were 8 in leek, 7 in paprika, and 10 in tea. Representative MRM chromatograms demonstrated clear, resolved peaks for compounds such as carbofuran, propoxur, and tricyclazole at low levels. Automated peak selection based on the largest MRM response enabled identification without prior retention time information.

Benefits and Practical Applications

Implementing a universal high-speed MRM workflow offers several advantages:

• Reduced method development time by eliminating compound-specific optimization.
• High throughput screening suitable for routine food safety and regulatory labs.
• Consistent sensitivity and selectivity across a broad pesticide panel.
• Automated data processing streamlines identification and reporting.

Future Trends and Opportunities

Advancements may include:

• Integration of high-resolution accurate-mass (HRAM) detection for confirmatory analysis.
• Machine learning algorithms for improved false positive filtering and compound identification.
• Expansion of universal libraries to cover emerging contaminants and metabolites.
• Automation of sample preparation and data workflows for fully unattended screening.

Conclusion

The universal LC-MS/MS method demonstrated rapid, sensitive, and reliable screening of over 170 pesticides in complex food matrices. By using fixed MRM parameters and high acquisition speeds, laboratories can achieve robust detection at low ppb levels without extensive method optimization, paving the way for more efficient food safety monitoring.