Highly sensitive direct analysis of glyphosate, glufosinate and AMPA in the beverages by LC-MS/MS

Importance of the Topic

Analysis of glyphosate, glufosinate and their main degradation product AMPA is essential for monitoring environmental contamination and ensuring beverage safety. Regulatory limits demand sensitive detection of these highly polar herbicides in water and food matrices. A rapid and direct LC-MS/MS method without derivatization streamlines routine testing and supports compliance with stringent limits such as the 0.1 μg/L threshold in the EU.

Objectives and Study Overview

This work aimed to develop a direct, high-sensitivity LC-MS/MS assay for simultaneous quantification of glyphosate, glufosinate and AMPA in beverages and tap water. Key goals included eliminating time-consuming derivatization, minimizing sample preparation to simple filtration and dilution, and achieving reliable recovery and precision across diverse matrices.

Methodology and Instrumentation

Sample pretreatment involved only membrane filtration (0.22 μm) and 100-fold dilution. Separation was performed on a hydrophilic interaction liquid chromatography column (Shodex HILICpak VT-50 2D) using a 30-minute gradient of 50 mmol/L ammonium bicarbonate (pH 9) and acetonitrile. Detection employed negative-mode MRM on a Shimadzu LCMS-8050 triple quadrupole with heated ESI. Key conditions included:

• UHPLC system: Nexera X2 with PEEK tubing to prevent adsorption
• Column: HILICpak VT-50 2D, 150 × 2.0 mm, 5 μm
• Mobile phase A: 50 mmol/L ammonium bicarbonate in water; B: acetonitrile
• Flow rate: 0.25 mL/min; column temperature: 40 °C; injection volume: 50 μL
• MS source: ESI negative, DL 250 °C, interface 300 °C, block 400 °C
• MRM transitions: AMPA 110 > 78.8 (CE 28 V), glufosinate 180.1 > 62.9 (CE 43 V), glyphosate 168.1 > 62.9 (CE 24 V)

Results and Discussion

Calibration curves were linear from 0.1 to 100 μg/L (r2 > 0.998). The method LLOQ was 0.2 μg/L with precision (RSD < 6 %) and accuracy within 95–106 %. Recovery tests in seven beverages (coffee, tea, wines, juice, mineral water, beer) yielded 72.9–104.9 % with RSD < 11 %. Direct tap water analysis showed recoveries of 56.8–75.1 %, influenced by nitrate and sulfate levels; city water with higher NO3– showed reduced AMPA recovery. Matrix-matched calibration and standard addition effectively compensated for these effects.

Benefits and Practical Applications

The presented method offers rapid, derivatization-free analysis of polar herbicides in complex matrices. Minimal sample preparation reduces labor and risk of contamination. High sensitivity and robust recoveries enable reliable monitoring in environmental water and beverage quality control without extensive clean-up steps.

Future Trends and Opportunities

Further work may focus on automated on-line sample handling, evaluation of additional matrix interferences, and adaptation to high-throughput screening in regulatory labs. Integration with ion chromatography for simultaneous anion profiling and coupling to high-resolution MS could expand applicability to broader contaminant surveillance.

Conclusion

A direct LC-MS/MS assay was established for glyphosate, glufosinate and AMPA, achieving low detection limits, strong linearity and satisfactory recoveries in beverages and tap water. The simplified workflow supports efficient routine analysis and compliance with regulatory requirements.

References

• 27th Symposium on Environmental Chemistry (Okinawa, 2018) P-110, Japan Society for Environmental Chemistry