DEVELOPING A ROBUST LC-MS/MS METHOD FOR THE DETERMINATION OF ANIONIC POLAR PESTICIDES IN A RANGE OF FOODSTUFFS WITHOUT DERIVATIZATION

Importance of the Topic

Concerns over residues of highly polar anionic pesticides such as glyphosate in food have driven demand for reliable analytical methods. Traditional reversed phase chromatography offers poor retention of these compounds, necessitating alternative approaches to ensure food safety monitoring.

Objectives and Study Overview

This work aims to develop a robust UPLC-MS/MS method for the direct determination of a broad range of anionic polar pesticides in diverse food matrices without any derivatization or ion-pairing steps. The goal is to consolidate multiple target analytes into a single efficient workflow.

Methodology and Instrumentation

The extraction protocol follows the EURL QuPPe procedure using acidified acetonitrile to generate crude food extracts. Chromatographic separation employs a 2.1 × 100 mm, 5 µm ethylene bridged hybrid column functionalized with diethylamine ligands, providing both hydrophilic interaction and anion exchange retention. Analysis is performed on a UPLC-MS/MS platform (Xevo TQ-S micro), with two optimized gradient methods: Method A featuring buffered formic acid for broad applicability, and Method B using formic acid alone to enhance sensitivity.

Main Results and Discussion

Method B demonstrates excellent linearity (R2 > 0.995) in matrix-matched calibrations from 0.002 to 0.2 mg/kg, with accuracy within 70–120% and precision (RSD) below 15% across spiked wheat flour samples. Retention time stability remains within ±0.1 min over different commodities. Baseline separation is achieved for critical isobaric pairs such as AMPA, phosphonic acid, and fosetyl aluminum, eliminating false positives. Full-scan RADAR acquisition further allows assessment of matrix effects and potential ion suppression.

Benefits and Practical Applications

• Single extraction covers multiple polar analytes, improving laboratory throughput
• No derivatization or ion pairing reduces sample handling time
• Applicable to at least 13 target compounds including chlorate and perchlorate in one injection
• Fully compliant with SANTE guidelines for method validation

Future Trends and Potential Applications

Integration of high-resolution full-scan workflows could extend screening to emerging polar contaminants. Automated data processing using RADAR-like tools may streamline routine analysis. Further expansion to additional food commodities and adoption of targeted cleanup steps can improve robustness against complex matrices.

Conclusion

The described UPLC-MS/MS method delivers sensitive, precise, and reproducible quantification of anionic polar pesticides in food without derivatization, meeting regulatory requirements and enabling efficient surveillance.

References

1. European Union SANTE 11813/2017 Guidance Document on Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed
2. European Commission QuPPe Method, 2019
3. Chamkasem N and Harmon T, Anal Bioanal Chem 408(18):4995–5004, 2016