Determination of Chlormequat Chloride Residues in Cereals by LC-MS/MS

Significance of the Topic

Chlormequat chloride is a widely used plant growth regulator that influences plant morphology and yield. Regulatory limits vary by region, and sensitive analytical methods are critical to enforce maximum residue levels, support import tolerances, ensure food safety, and protect brand reputation in the face of public scrutiny around pesticide residues in cereals.

Objectives and Study Overview

This study evaluates a targeted LC-MS/MS approach for quantifying chlormequat chloride in cereal flours. Key goals include assessing method sensitivity, accuracy, precision, and suitability for regulatory compliance and due diligence testing.

Methodology

An established QuPPe extraction was applied followed by dilute-and-shoot analysis on a BEH Amide column. Method performance was validated according to SANTE guidelines with spiked wheat, buckwheat, and rye flour at 0.005 and 0.05 mg/kg. Two FAPAS QC materials were analyzed to verify accuracy.

Instrumentation Used

• ACQUITY Arc LC System
• Xevo TQ-S cronos Tandem Quadrupole Mass Spectrometer
• waters_connect software for data acquisition and quantitation

Key Results and Discussion

• Chromatographic retention time of chlormequat chloride was 1.35 min (void volume 0.34 min) in a 5 min run.
• Limit of quantification reached 0.005 mg/kg with clear signal and minimal matrix interferences.
• Calibration was linear over 0.0025–0.50 mg/kg (R2 ≥ 0.999) using a deuterated internal standard.
• Apparent recoveries ranged from 94 to 102% with repeatability (RSDr) below 4%.
• QC reference materials confirmed accuracy against assigned values.

Benefits and Practical Applications

• Single extraction and analysis workflow for polar cationic residues in cereals.
• Suitable for monitoring compliance with MRLs, import tolerances, and zero tolerance requirements.
• Supports food industry due diligence and brand protection at low residue levels.
• Quick turnaround with limited sample preparation and cost-effective instrumentation.

Future Trends and Opportunities

Analytical developments may extend this approach to other polar pesticides and processed cereal products. Integration with high-resolution mass spectrometry, lower detection limits, and automated data workflows will enhance routine testing and regulatory monitoring.

Conclusion

The evaluated LC-MS/MS method for chlormequat chloride in cereals provides sensitive, accurate, and reproducible results. Its compliance with SANTE guidelines and performance on QC materials demonstrates readiness for official control, due diligence, and brand protection testing in cereal commodities.

References

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4. European Commission Regulation (EU) 2019/552 on MRLs for pesticides. 2019.
5. US Federal Register. Import tolerances for chlormequat chloride. 2020.
6. US CFR Title 40. Section 180.5 on tolerances and exemptions. 2024.
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9. European Commission Implementing Regulation 2023/731 on pesticide control programme. 2023.
10. Waters Application Note 720007201. Determination of Polar Pesticides Using UPLC-MS/MS. 2021.
11. SANTE/11312/2021 V2 Guidance on Analytical Quality Control and Method Validation for Pesticide Residues. 2024.