Routine analysis of polar pesticides in water at low ng/L levels by ion chromatography coupled to triple quadrupole mass spectrometer

Importance of the Topic

Polar pesticides such as glyphosate, AMPA, glufosinate, fosetyl-Al and clopyralid can contaminate surface and drinking waters at trace levels. Sensitive and robust analytical methods are essential to ensure compliance with regulatory limits and to protect public health.

Study Objectives and Overview

This work aimed to develop and validate an IC-MS/MS method for high-throughput screening and quantitation of five polar pesticide residues and their metabolites in water matrices at levels below current legislative requirements.

Methodology and Instrumentation

• Sample preparation: direct injection for drinking and bottled mineral water; filtration of surface water samples.
• Chromatographic separation: Dionex Integrion HPIC system with IonPac AS24 column and electrochemical suppressor; KOH gradient generated in situ.
• Mass spectrometry: TSQ Quantiva triple quadrupole in negative SRM mode, heated ESI source, optimized collision energies.
• Make-up flow: isopropanol addition to enhance desolvation and improve ionization efficiency.

Instrumentation Used

• Thermo Scientific TSQ Quantiva Triple Quadrupole MS
• Thermo Scientific Dionex Integrion HPIC System
• ASRS 300 Anion Electrolytically Regenerated Suppressor
• Dionex IonPac AS24 Analytical and AG24 Guard Columns
• PES Syringe Filters and Auxiliary Pumps for make-up flow

Main Results and Discussion

• LOQs ranged from 5 to 50 ng/L in real water matrices; clopyralid LOQ = 50 ng/L, elevated to 500 ng/L in high-salt artificial matrix.
• Recoveries between 84 % and 139 % with RSDs below 15 % across drinking, bottled, and surface water samples.
• Matrix effects were minimal for glyphosate but significant for clopyralid under high ionic strength; matrix-matched calibration was employed.
• The IC-MS/MS method matched or exceeded performance of a derivatization-based LC-MS/MS approach without requiring time-consuming sample preparation.

Benefits and Practical Applications

The direct IC-MS/MS workflow eliminates derivatization steps, reduces overall analysis time, increases sample throughput, and broadens the range of detectable polar analytes. It is well suited for routine environmental and drinking water monitoring laboratories.

Future Trends and Applications

• Expansion to additional ionic and polar contaminants and their transformation products.
• Integration with automated sample preparation and high-resolution mass spectrometry for non-target screening.
• Development of portable IC-MS systems for on-site environmental monitoring.
• Adoption of green analytical practices through advanced eluent generation and reduced reagent consumption.
• AI-driven data processing workflows for rapid decision support.

Conclusion

The validated IC-MS/MS method provides a sensitive, robust, and efficient solution for the analysis of polar pesticides in diverse water matrices, supporting compliance with stringent water quality regulations while streamlining laboratory workflows.

Reference

1. IARC Q&A on Glyphosate Carcinogenicity, 2017.
2. EFSA Assessment of Glyphosate Toxicology, 2015.
3. EU Regulation 396/2005 on Pesticide Maximum Residue Levels.
4. Hanke I. et al., Anal Bioanal Chem, 2008;391(6):2265–2276.
5. QUPPE Pesticide Analysis Database.
6. In-house FMOC Derivatization LC-MS/MS Method, Povodi Vltavy, Czech Republic.
7. Eurachem Guide 2014: Method Validation and Laboratory Quality.
8. EU Council Directive 98/83/EC on Drinking Water Quality.