Analysis of Glufosinate, Glyphosate, and AMPA in Tap Water Using Triple Quadrupole LC/MS/MS

Significance of the Topic

Monitoring trace levels of glufosinate, glyphosate, and AMPA in drinking water is essential to ensure public health and comply with regulatory limits defined by health agencies such as Japan’s Ministry of Health, Labour and Welfare.

Objectives and Study Overview

This work presents a direct triple quadrupole LC/MS/MS approach using FMOC derivatization to quantify glufosinate, glyphosate, and their metabolite AMPA in tap water without the need for solid-phase extraction concentration. The method targets analyte levels at or below 1/100 of Japanese regulatory thresholds.

Methodology and Instrumentation

The protocol follows Appendix Method 22 with the following key steps:

• Sample derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl) under basic conditions at 50 ˚C for 20 min.
• Quenching of reaction with phosphoric acid and direct injection into the LCMS system.

Key analytical parameters on the Shimadzu Nexera X3–LCMS-8050 system include:

• HPLC: Mastro 2 C18 column (100 mm × 2.0 mm, 3 μm), gradient elution with 5 mmol/L ammonium acetate (A) and acetonitrile (B).
• Flow rate: 0.25 mL/min, column temperature: 40 ˚C, injection volume: 20 μL.
• MS/MS: ESI negative mode, MRM transitions m/z 402.10>180.10 for glufosinate, 390.05>168.05 for glyphosate, and 332.05>110.05 for AMPA.

Main Results and Discussion

Linear calibration curves (0.1–3 μg/L) showed correlation coefficients (r²) greater than 0.998 for all analytes. The method achieved detection at 0.1 μg/L, one-hundredth of regulatory limits.
Spike-and-recovery tests in chlorinated tap water (n=5) yielded:

• Glufosinate: 97 % recovery, 2.0 % RSD.
• Glyphosate: 91 % recovery, 6.3 % RSD.
• AMPA: 89 % recovery, 4.0 % RSD.

These results confirm high sensitivity, accuracy, and precision without solid-phase extraction.

Benefits and Practical Applications

• Rapid, direct analysis of target herbicides at ultratrace levels in drinking water.
• Elimination of SPE concentration reduces sample preparation time and potential losses.
• Compliance with stringent water quality guidelines for regulatory monitoring and environmental assessment.

Future Trends and Possibilities

Advancements in LC/MS technology and derivatization strategies may enable multiplexed detection of a broader range of polar contaminants. Integration with automated sample handling and data processing could streamline high-throughput water quality surveillance.

Conclusion

The developed FMOC-derivatized LCMS-8050 method provides a sensitive, precise, and efficient solution for quantifying glufosinate, glyphosate, and AMPA in tap water below regulatory thresholds without solid-phase extraction.

References

1. Enactment of Ministerial Ordinances on Water Quality Standards and Partial Revisions to Waterworks Law Enforcement Regulations and Points to Note in Waterworks Water Quality Control (October 10, 2003; Final revision March 30, 2020), Appendix 4, Inspection Methods for Complementary Items to Set the Targets for Water Quality Management.