Direct Analysis of Glyphosate, Glufosinate and AMPA in Foods Using a Triple Quadrupole LC/MS/MS

Importance of the Topic

Glyphosate, glufosinate and their primary metabolite AMPA are widely used non-selective herbicides whose residues in food commodities are strictly regulated. Reliable detection of these highly polar compounds without time-consuming derivatization is critical for food safety monitoring, regulatory compliance and protection of public health.

Objectives and Study Overview

This study presents a direct analysis method for glyphosate, glufosinate and AMPA in various food matrices (grains, flour, oats, soybeans and grapes) using the QuPPe sample-preparation protocol coupled with triple quadrupole LC/MS/MS. Key aims included:

• Developing a workflow that eliminates derivatization steps.
• Achieving low limits of quantification down to 0.5 ng/mL in final extract.
• Validating recovery, precision and linearity across representative food products.

Methodology and Instrumentation Used

Sample pretreatment followed the QuPPe protocol optimized for high-protein/lipid commodities:

• Weigh sample (1–10 g) into centrifuge tube.
• Add water, internal standards, formic acid–methanol mixture and aqueous EDTA.
• Shake, centrifuge (13 000 g, –9 °C), filter (0.22 μm) and ultrafiltrate (3 kDa cutoff).
• Mix extract with acetonitrile, vortex, centrifuge and inject 5 μL into LC/MS/MS.

Instrumentation details:

• UHPLC: Shimadzu Nexera X2 with RESTEK Polar X column (30 × 2.1 mm, 2.7 μm), gradient 60% B to 5% B (B = 0.1% formic acid in acetonitrile), flow 0.6 mL/min, 35 °C.
• Mass spectrometer: Shimadzu LCMS-8060 triple quadrupole, ESI in negative mode, PEEK tubing to minimize adsorption.
• Multiple reaction monitoring transitions optimized for each analyte and isotope-labelled internal standard.

Main Results and Discussion

Calibration and sensitivity:

• Linear range 0.5–100 ng/mL with correlation coefficients (R2) ≥ 0.999 for all compounds.
• Lower limit of quantification 0.5 ng/mL; instrumental LOD ~2.5 pg.

Precision and accuracy:

• Intra-day repeatability (RSD) ≤ 10% at 0.5 ng/mL level.
• Recoveries in real food samples ranged 90–100% with RSD ≤ 10%.

Matrix application:

• Analysis of flour, whole grain flour, oats, soybeans and grapes spiked at 1 mg/kg showed no significant matrix interference.
• Measured residues were below established MRLs in all tested products.

Benefits and Practical Applications

This direct LC/MS/MS approach offers:

• Elimination of laborious derivatization, reducing sample preparation time.
• High sensitivity and reproducibility suitable for routine QA/QC labs.
• Broad applicability across diverse food commodities under QuPPe guidance.

Future Trends and Opportunities

Potential developments include:

• Extension to additional polar pesticide residues and metabolites.
• Integration with high-resolution mass spectrometry for non-target screening.
• Automation of QuPPe workflows for high-throughput monitoring.
• Standardization of direct-analysis protocols in international food safety regulations.

Conclusion

The presented method enables sensitive, accurate and reproducible quantification of glyphosate, glufosinate and AMPA in food matrices without derivatization. It meets regulatory MRL requirements and supports efficient routine monitoring in food safety laboratories.

Reference

• European Commission. QuPPe Method. (2019)
• Commission Regulation (EU) No 441/2012 of 24 May 2012.
• Codex Alimentarius. Pesticide Residues in Food Online Database (Glyphosate No. 158).
• Ministry of Health, Labour and Welfare, Japan. Public Notice No. 361 of 2017.