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Significance of the Topic

Effective weed control in agriculture relies on phenoxypropionic herbicides, which combine high efficacy with low mammalian toxicity. Simultaneous monitoring of multiple herbicide residues is essential to ensure food safety and regulatory compliance.

Objectives and Study Overview

This study aimed to develop and validate a fast, sensitive LCMS method for the simultaneous determination of four phenoxy herbicides: fluazifop, fluazifop-butyl, quizalofop and quizalofop-ethyl. The approach focused on achieving low detection limits, excellent linearity and efficient chromatographic separation.

Methodology and Instrumentation

The method used reversed-phase high-performance liquid chromatography with a semi-micro C18 column and electrospray ionisation in both negative and positive modes. Selected ion monitoring (SIM) allowed selective detection of carboxylic acids in negative mode and ester derivatives in positive mode. Rapid polarity switching enhanced throughput.

Instrumentation

• Single quadrupole LCMS-2010 system
• Electrospray ionisation source
• Semi-micro C18 HPLC column
• SIL-HT autosampler with 15 second injection cycle

Main Results and Discussion

Baseline separation of all four herbicides was achieved in under 30 minutes. Calibration curves from 0.8 to 500 ppb exhibited excellent linearity (r2 > 0.9999). Sensitivity gains were attributed to optimized column dimensions and fast switching, enabling detection at sub-ppb levels. Chromatograms and mass spectra confirmed characteristic m/z signals for each compound.

Practical Benefits and Applications

• Routine residue analysis in agricultural products and medicinal herbs
• Multi-residue screening in regulatory laboratories
• Quality control in pesticide manufacturing

Future Trends and Opportunities

Future enhancements may include high-resolution mass spectrometry for non-targeted screening, ultra-fast HPLC gradients to reduce analysis time further, and integration of microflow techniques to boost sensitivity and reduce solvent consumption.

Conclusion

The presented LCMS method offers a robust, high-throughput solution for simultaneous analysis of phenoxypropionic herbicides with sub-ppb sensitivity and outstanding linearity, supporting stringent monitoring requirements in agriculture and food safety.