Analysis of Glyphosate and AMPA in Environmental Water Samples by Ion Chromatography and On-Line Mass Spectrometry with Minimal Sample Preparation

Significance of the topic

Glyphosate and its primary metabolite AMPA are widely applied herbicides that often enter surface and effluent waters. Accurate monitoring of these compounds at trace levels is critical for environmental risk assessment, regulatory compliance and ensuring water quality. Traditional approaches rely on derivatization steps that increase complexity and analysis time. A streamlined technique using ion chromatography coupled directly to tandem mass spectrometry offers minimal sample preparation and high sensitivity.

Objectives and Study Overview

This study aimed to develop and validate a simple, robust high-performance ion chromatography-MS/MS (IC-MS/MS) method capable of detecting glyphosate and AMPA in environmental water matrices without laborious derivatization. Surface and effluent water samples were investigated to demonstrate the approach under realistic conditions.

Methodology and Instrumentation

The analytical workflow used a high-capacity Thermo Scientific Dionex ICS-2100 system with an AG24/AS24 anion-exchange column allowing direct injection of samples with elevated ionic content. A KOH gradient (30–40 mM) was generated on-line by an eluent generator, and a self-regenerating ASRS 300 suppressor desalinated the eluate prior to detection.

• Chromatographic conditions: 0.25 mL/min flow rate, 30 °C column temperature, 50 µL injection volume.
• Mass spectrometry: Thermo Scientific TSQ Vantage triple-quadrupole in negative ion SRM mode; transitions selected were 168→79 and 168→63 for glyphosate, 110→79 and 110→63 for AMPA.

Main Results and Discussion

The optimized method achieved baseline separation of glyphosate, AMPA and common inorganic anions (chloride, sulfate, nitrate) under gradient conditions. Calibration curves were linear from 1 to 50 µg/L for both analytes (R² > 0.99). A spiked surface water sample at 2 µg/L was readily quantified by MS/MS, whereas conductivity detection alone could not detect these levels.

Benefits and Practical Applications

The approach eliminates derivatization, reduces sample handling and shortens analysis time. It provides low-microgram-per-liter detection limits suitable for environmental monitoring of agricultural runoff, effluent discharge and could be adapted for routine QA/QC laboratories.

Future Trends and Potential Applications

Future work will aim to further lower detection limits for drinking water compliance and expand the method to cover additional glyphosate metabolites. Integration with automated sample preparation and high-throughput workflows could broaden its industrial and regulatory applications.

Conclusion

The straightforward IC-MS/MS method successfully quantifies glyphosate and AMPA in water with minimal preparation, robust performance and sensitivity comparable to derivatization-based LC-MS/MS protocols. This strategy is well-suited for environmental monitoring and potential expansion to other polar agrochemical residues.

References

1. You J.; Koropchak J. A. Condensation nucleation light scattering detection with ion chromatography for direct determination of glyphosate and its metabolite in water. J. Chromatogr. 2003, 989, 231–238.
2. Yang C.; Henday S.; Wang L.; Schnute B. Analysis of Glyphosate and AMPA in Environmental Water by Ion Chromatography Electrospray Tandem Mass Spectrometry (IC-ESI-MS/MS). Application Note 491, Thermo Fisher Scientific Inc., 2010.