Multi-class pesticides analysis in challenging vegetable matrices using fast 5 msec MRM with 15 msec polarity switching

Significance of the Topic

Multi-class pesticide monitoring in vegetable matrices is critical for ensuring consumer safety and complying with diverse regulatory limits. Rapid, comprehensive screening methods reduce the risk of trade disruptions caused by varying national maximum residue limits and support high-throughput testing in food safety laboratories.

Objectives and Study Overview

This study evaluates an ultra-fast multiple reaction monitoring (MRM) approach with 5 millisecond dwell time and 15 millisecond polarity switching to screen 138 pesticides in challenging vegetable matrices. The method aligns with the European Union Reference Laboratory (EURL) guidelines, combining liquid and gas chromatography triple quadrupole systems to maximize coverage.

Methodology and Instrumentation

Sample preparation followed the QuEChERS EU protocol. Vegetables were homogenized, extracted with acetonitrile and buffered salts, and cleaned by dispersive solid-phase extraction with MgSO4, PSA and ENVI-Carb sorbents. Analytical conditions included:

• Chromatography: UHPLC with a C18 column, gradient elution from 5 to 100% methanol in 20 minutes at 0.2 mL/min and 40°C.
• MS Detection: Triple quadrupole mass spectrometer operating in electrospray ionization (positive/negative) with fast polarity switching.
• Transitions: 276 MRM channels at 5 ms dwell time and 1 ms pause time.

Instrumentation Used

The analysis employed a Shimadzu Nexera UHPLC coupled to an LCMS-8040 triple quadrupole system. Key features included:

• Ultra-fast scan speed (15000 u/sec).
• Fast MRM transition capability (555 channels/sec).
• Enhanced sensitivity over earlier models.

Key Results and Discussion

• Limits of quantification (LOQs) for all 72 LC-amenable pesticides were below 10 ppb. For GC-amenable compounds, 71% achieved LOQs under 10 ppb.
• Calibration curves showed linear responses across low concentration ranges, demonstrating reliable quantitation down to regulatory MRL levels.
• Recovery rates in paprika and leek matrices were satisfactory, with approximately 90% of pesticides falling within 70–120% recovery. A small number of analytes detected in blanks indicated minor matrix interferences.

These results confirm the method’s robustness for multi-class screening in complex plant samples.

Benefits and Practical Applications

• Simultaneous detection of a broad pesticide spectrum reduces analysis time and resource requirements.
• Fast polarity switching and high-throughput capability support routine monitoring laboratories in meeting diverse regulatory standards.
• The approach can replace separate GC and LC workflows for many compounds, streamlining operations.

Future Trends and Potential Applications

Advances may include expanded analyte libraries, integration with high-resolution mass spectrometry for non-targeted screening, automation of sample preparation, and application in on-site or field-deployable platforms. Machine learning algorithms could further enhance data processing and compound identification.

Conclusion

The ultra-fast MRM approach with rapid polarity switching enables comprehensive, sensitive pesticide screening in vegetable matrices. The method meets stringent LOQ requirements and streamlines workflows, offering a versatile solution for modern food safety challenges.

Reference

No specific literature references were provided in the source text.