Analysis of Glyphosate, Glufosinate, and AMPA in Tap and Surface Water Using Open-Architecture UPLC with 2D-LC Technology

Importance of the Topic

Glyphosate is a broadly applied herbicide that degrades to AMPA and poses potential contamination risks for surface and drinking water. Its analysis is challenging due to high polarity, low volatility, and lack of chromophores, requiring derivatisation and sensitive detection strategies to ensure public health protection.

Study Objectives and Overview

The primary goal was to develop an automated two dimensional liquid chromatography method with open architecture UPLC for simultaneous quantification of glyphosate, glufosinate, and AMPA in tap and surface water at trace levels (ppb). The workflow integrates online derivatisation, sample enrichment, and high resolution separation to reduce manual steps and improve throughput.

Methodology

An automated derivatisation protocol was implemented using 9-fluorenylmethyl chloroformate (FMOC-Cl) under controlled pH and temperature. Following acidification of 10 mL water samples, acetonitrile and borate buffer were added, and the FMOC-Cl reaction was carried out at 60 °C for 30 minutes. The reaction was quenched by acid addition to stabilize derivatives. A 0.5 mL aliquot of the final mixture (aqueous/ACN 2:1) was loaded via at-column dilution onto a trap column for enrichment prior to analysis.

Instrumentation

• Open-architecture ACQUITY UPLC system with two-dimensional LC and at-column dilution
• Xevo TQ MS operated in positive electrospray ionization mode
• Trap column: Oasis HLB for sample enrichment
• Analytical column: ACQUITY UPLC BEH C18 (2.1 × 50 mm, 1.7 µm) at 60 °C

Key Results and Discussion

The method achieved limits of quantification at 1 µg/L for all analytes with linear calibration from 1 to 200 µg/L (r2 > 0.99). Automated peak focusing via 5% at-column dilution improved peak shape and reproducibility (CV ~2% for n=8). FMOC derivatives remained stable for at least 24 hours. Analysis of environmental samples showed glufosinate, glyphosate, and AMPA at 21.8, 12.8, and 18.4 µg/L respectively in surface water, and sub-ppb levels in tap water, demonstrating sub-µg/L detection capabilities.

Benefits and Practical Applications

• Minimal sample preparation limited to filtration
• Automated derivatisation reduces labor and operator error
• Two-dimensional LC enhances selectivity and sensitivity
• Applicable for routine monitoring and regulatory compliance

Future Trends and Potential Uses

The platform can be extended to other highly polar contaminants by adapting derivatisation agents. Integration with photodiode array detection could lower costs. Further automation, miniaturization, and green chemistry approaches will likely enhance throughput and sustainability in environmental and industrial analytics.

Conclusion

This automated 2D-UPLC method provides sensitive, reproducible, and rapid analysis of glyphosate, glufosinate, and AMPA in water. It meets regulatory requirements, reduces manual handling, and offers a versatile workflow for trace-level monitoring of polar agrochemicals.

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