Measurement of Underivatized Glyphosate and Other Polar Pesticides in Aqueous Matrices Using LC-TQ

Importance of the Topic

Glyphosate is a globally prevalent, broad-spectrum herbicide whose polar nature and chelating properties complicate direct analysis in environmental and food matrices. Reliable monitoring is critical for regulatory compliance and environmental safety, driving demand for robust, sensitive methods that avoid derivatization and handle diverse aqueous samples.

Study Objectives and Overview

This application note presents an integrated workflow combining streamlined sample preparation, specialized reversed-phase chromatography, and triple quadrupole mass spectrometry to quantify glyphosate, AMPA, glufosinate, N-acetylglufosinate (NAG), HEPA, MPPA, ethephon, and fosetyl in water, wine, and other matrices. The goal is high sensitivity, reproducibility, and throughput with minimal sample handling.

Methodology

Sample preparation for surface and drinking water involves centrifugation or filtration through a 0.2 µm PES membrane followed by acidification with 0.1 % formic acid. Wine samples are filtered, diluted (1:9), then acidified. Chromatography uses an InfinityLab Poroshell 120 CS-C18 column (2.1×150 mm, 2.7 µm) with a mobile phase of 0.1 % formic acid (5 µM deactivator additive) in water (A) and 0.1 % formic acid in methanol (B). A gradient from 99.9 % A to 100 % B over 8 min at 0.35 mL/min separates analytes without peak tailing.

Použitá instrumentace

• Agilent 1290 Infinity II UHPLC with PEEK-lined flow path (needle seat, rotor seal, capillaries, Quick Turn fittings)
• Agilent InfinityLab Poroshell 120 CS-C18 column, P/N 693775-942
• Agilent 6470 Triple Quadrupole LC/MS with JetStream ESI

Main Results and Discussion

Retention times ranged from 0.95 min (AMPA) to 5.0 min (fosetyl) with sharp peaks and minimal metal-related tailing. Calibration curves showed excellent linearity (R2 ≥ 0.998) over 10–10,000 ng/L (varies by compound). Limits of quantitation as low as 10–25 ng/L enabled method detection limits below regulatory thresholds. MDL for glyphosate was 6.1–8.6 ng/L at 10 ng/L on-column injections.

Benefits and Practical Applications

• No derivatization or complex extraction steps required
• Compatible with positive and negative polarity MRM transitions
• High throughput: 8-min runs with large aqueous injections
• Robust performance across environmental and food matrices

Future Trends and Possibilities

Advancements may include miniaturized LC systems, faster superficially porous columns for sub-minute separations, automation for on-site testing, and integration of high-resolution MS or AI-driven data processing to broaden the scope to emerging polar contaminants.

Conclusion

The described all-Agilent workflow delivers a sensitive, reproducible, and user-friendly approach for direct analysis of glyphosate and related polar pesticides in complex aqueous matrices, meeting stringent regulatory and research requirements.

Reference

• Pest Management Science 64:319–325 (2008)
• Analytical Chemistry 2018, 90, 9457–9464
• US EPA Clean Water Act Analytical Methods