Detection of Anionic Polar Pesticides in Food Samples Using the Xevo TQ Absolute With Sub μg/kg Limits of Quantification

Significance of the Topic

The detection of anionic polar pesticides in food is critical to ensure consumer safety and regulatory compliance. These highly water-soluble compounds often evade traditional multi-residue methods and require sensitive, robust workflows to achieve sub-microgram per kilogram quantification in diverse food matrices.

Objectives and Overview

This study evaluates the performance of the Xevo TQ Absolute tandem quadrupole mass spectrometer combined with the QuPPe generic extraction protocol for multi-residue analysis of anionic polar pesticides. The main goals are to establish low limits of quantification in representative vegetable (cucumber) and cereal (wheat flour) samples, assess method trueness and repeatability, and demonstrate reduced matrix effects via lowered sample injection volumes.

Instrumentation

The analytical platform integrates:

• Xevo TQ Absolute tandem quadrupole mass spectrometer with enhanced negative-ion sensitivity
• Ultra-high-performance liquid chromatography system equipped with an Anionic Polar Pesticide Column
• Standard LC-MS/MS configuration for QuPPe v12 extracts

Methodology

Sample preparation followed the QuPPe version 12 protocol using acidified methanol extraction. Cucumber standards ranged from 0.5 to 200 µg/kg (in-vial 0.25–100 ng/mL) and wheat flour standards from 2 to 200 µg/kg (0.25–25 ng/mL). Calibration curves were generated in corresponding matrix extracts, with internal standards applied to all analytes except ethephon. Chromatographic separation employed the proprietary Anionic Polar Pesticide Column under previously established conditions.

Main Results and Discussion

Linearity across both matrices exhibited r2 ≥ 0.99 and residuals below 20% for all compounds. Method limits of quantification (LOQ) defined as the lowest detectable calibration level were:

• Cucumber: 0.5 µg/kg for all targets
• Wheat flour: 2 µg/kg for most analytes; AMPA at 5 µg/kg due to matrix suppression

Trueness and repeatability (n=10) were evaluated at low and mid-range concentrations:

• Cucumber (1 & 10 µg/kg): mean recoveries 91–117%, RSDs 0.6–8.7%
• Wheat flour (10 & 50 µg/kg): mean recoveries 96–104%, RSDs 0.5–9.2%

Long-term injection repeatability (30 injections of 10 µg/kg cucumber standard) yielded peak area RSDs ≤3% for most analytes; Fosetyl Al recorded 7% due to ionization variability.

Benefits and Practical Applications

• Achieves sub-µg/kg quantification in diverse food matrices
• Supports multi-residue testing with a single generic extraction protocol
• Reduces matrix load and maintenance via lower injection volumes
• Facilitates global implementation with outcome-based support

Future Trends and Applications

Continued advancements may include:

• Further sensitivity enhancements through novel ion optics and source designs
• Expanded multi-residue panels covering emerging polar compounds
• Automation of QuPPe extraction to increase throughput
• Integration of high-resolution MS and AI-driven data analysis for improved selectivity

Conclusion

The Xevo TQ Absolute, paired with QuPPe extraction and an Anionic Polar Pesticide Column, delivers reliable multi-residue analysis of anionic polar pesticides at sub-µg/kg levels. Robust linearity, excellent trueness, and high repeatability demonstrate its suitability for routine food safety testing and regulatory monitoring.

Reference

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