SUB 1 μG/KG DETECTION OF GLYPHOSATE AND OTHER ANIONIC POLAR PESTICIDES USING A GENERIC EXTRACTION AND DETECTION BY LC-MS/MS

Significance of the topic

Anionic polar pesticides such as glyphosate and its metabolites present analytical challenges due to their high polarity and negative charge which limit compatibility with conventional multi residue methods and reversed phase LC. Monitoring these compounds at sub microgram per kilogram levels is critical for food safety regulatory compliance and consumer protection

Objectives and Overview

The study aimed to develop a generic workflow combining the Quick Polar Pesticides extraction protocol with high sensitivity LC MS MS detection to achieve detection of glyphosate and related anionic polar pesticides below one microgram per kilogram in representative food matrices. The research focused on method performance in cucumber and wheat flour as model matrices and explored the potential to reduce injection volume while maintaining sensitivity

Methodology and Instrumentation

• Sample preparation via QuPPE version 12 for wet commodities cucumber and dry commodities wheat flour
• Calibration standards prepared from 0.5 to 200 microgram per kilogram for cucumber and 2 to 200 microgram per kilogram for wheat flour
• Chromatographic separation on Waters Anionic Polar Pesticide Column 2.1 x100 mm 5 micron with formic acid acidified water and acetonitrile gradient
• Detection on Xevo TQ Absolute triple quadrupole MS operating in negative electrospray ionization mode
• MRM transitions optimized for ten anionic polar pesticides including glyphosate N Acetyl glyphosate AMPA and others

Main Results and Discussion

• Limits of quantification as low as 0.5 microgram per kilogram in cucumber and 2 microgram per kilogram in wheat flour for most analytes with slightly higher LOQ of 5 microgram per kilogram for AMPA in wheat flour due to matrix suppression
• Linear calibration achieved over 0.5 to 200 microgram per kilogram with R2 greater than 0.99 and residuals below 20 percent
• Peak area repeatability across 30 injections showed relative standard deviations below 3 percent for most analytes confirming method robustness
• Reduced injection volume enabled by enhanced sensitivity decreases matrix load on LC MS MS system improving long term performance

Benefits and Practical Applications

• Generic extraction workflow applicable to diverse food matrices without additional cleanup
• High sensitivity detection allows reliable quantification at regulatory relevant levels and supports expanded monitoring programs
• Maintenance of method performance with lower injection volumes enhances system robustness and reduces maintenance frequency
• Suitable for routine food safety laboratories requiring multi residue polar pesticide analysis

Used Instrumentation

• ACQUITY UPLC I Class PLUS system with sample manager FL
• Waters Anionic Polar Pesticide Column 2.1 x100 mm 5 micron
• Xevo TQ Absolute triple quadrupole mass spectrometer in negative ESI mode

Future trends and opportunities for use

• Integration of ion chromatography and high resolution mass spectrometry for extended analyte coverage
• Automation of sample preparation to further increase throughput
• Method adaptation to additional challenging matrices such as high lipid or high sugar samples
• Application to broader classes of highly polar contaminants including environmental pollutants and metabolites

Conclusion

The combination of the QuPPE generic extraction protocol with the high sensitivity detection capabilities of the Xevo TQ Absolute system provides a robust workflow for reliable quantification of anionic polar pesticides at sub microgram per kilogram levels in diverse food matrices. Method validation in cucumber and wheat flour demonstrates low limits of quantification excellent linearity and repeatability while reduced injection volumes enhance system longevity

References

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