Highly sensitive analysis of glyphosate, glufosinate and AMPA in the tap water and the beverages by LC-MS/MS without derivatization

Importance of the Topic

Monitoring glyphosate, glufosinate and their metabolite AMPA in drinking water and beverages is critical due to widespread herbicide use, potential health risks and stringent regulatory limits. Traditional methods require time-consuming derivatization steps to retain these highly polar compounds on reversed-phase columns. A rapid, sensitive direct analysis without derivatization streamlines workflow and meets low-level quantification requirements.

Study Aims and Overview

This study aimed to develop and validate an LC-MS/MS method for direct quantification of glyphosate, glufosinate and AMPA in tap water, beer, white wine and red wine without derivatization. Key objectives included optimizing chromatography to overcome weak retention, demonstrating method sensitivity and accuracy across relevant concentration ranges, and applying simple pretreatment procedures.

Methods and Instrumentation

Sample pretreatment involved only filtration and dilution for tap water, with an additional SPE cleanup step for beverages to reduce matrix interference. Analysis employed a Shimadzu Nexera X3 UHPLC system coupled to an LCMS-8060 triple quadrupole mass spectrometer in negative ESI mode. A HILIC column (RESTEK Polar X, 30×2.1 mm, 2.7 µm) and a gradient of 0.5% formic acid in water (A) and 0.1% formic acid in acetonitrile (B) were used at 0.6 mL/min. Key MRM transitions were 110.00 > 79.00 for AMPA, 179.80 > 63.00 for glufosinate and 167.90 > 62.80 for glyphosate. Stable isotope-labeled internal standards ensured accurate quantitation.

• UHPLC Conditions: RESTEK Polar X column, gradient B conc. from 80% to 0%, column temperature 35 °C, injection volumes 50 µL (water) or 5 µL (beverages).
• MS Conditions: ESI negative, ion source temperatures DL 250 °C, interface 350 °C, heat block 400 °C; nebulizer 2 L/min, drying 20 L/min, CID gas 325 kPa.

Key Results and Discussion

Calibration curves from 0.1 to 10 µg/L exhibited excellent linearity with accuracy between 87.7% and 118.8% and repeatability (%RSD) below 15%. Tap water recovery ranged from 70.4% to 99.6% (RSD < 16%). In beverages, glyphosate and glufosinate recoveries were 82.6%–109.4% with RSD below 14%. AMPA showed good recovery in beer (90.6%) and white wine (85.4%), but was not detected in red wine due to ion suppression by matrix impurities, indicating a need for further matrix optimization.

Benefits and Practical Applications

The direct LC-MS/MS approach eliminates derivatization, reducing analysis time and complexity. High sensitivity and robust performance make it well suited for routine monitoring in environmental and food safety laboratories, supporting regulatory compliance and quality control of drinking water and beverage products.

Future Trends and Potential Applications

Further work may focus on enhanced cleanup strategies to overcome matrix suppression for AMPA in complex beverages, automation of sample preparation, online SPE integration, and extension of this HILIC-MS/MS approach to other polar contaminants. Advances in high-resolution mass spectrometry and novel stationary phases may further improve sensitivity and selectivity.

Conclusion

This study presents a robust and sensitive direct LC-MS/MS method for glyphosate, glufosinate and AMPA analysis without derivatization. It delivers reliable quantitation in tap water and common beverages with simplified pretreatment, meeting low-level detection requirements and facilitating high-throughput monitoring.

Reference

[1] Ishioka K, Kawashima M, Kobayashi M, Masuda J, Hayakawa Y. Highly sensitive analysis of glyphosate, glufosinate and AMPA in tap water and beverages by LC-MS/MS without derivatization. 67th ASMS Conference on Mass Spectrometry, TP-216, Atlanta 2019.