Food Safety Solutions - Application Data Book

Simultaneous Determination of 13 Aryloxyphenoxypropionate Herbicides in Carrot by GC-MS/MS

Significance of the Method

Monitoring aryloxyphenoxypropionate (AOPP) herbicides in root vegetables is critical for food safety. AOPP herbicides such as diclofop-methyl and fenoxaprop protect crops from grassy weeds but may persist in edible tissues. A rapid, sensitive multi-residue assay ensures compliance with maximum residue limits and protects consumer health.

Target Compounds

The method quantifies 13 AOPP herbicides: diclofop-methyl, chlorazifop, fluazifop-P, quizalofop-P-ethyl, clodinafop-propargyl, fenoxaprop-P, haloxyfop-P, quizalofop-P-tefuryl, cycloxydim, propaquizafop, sethoxydim, clethodim, and tralkoxydim.

Sample Pretreatment (QuEChERS)

• Weigh 10 g finely chopped carrot into a 50 mL centrifuge tube.
• Add 10 mL acetonitrile containing 1% acetic acid, shake vigorously for 1 min.
• Add 4 g MgSO₄ and 1 g NaCl, shake for 1 min, then centrifuge 5 min at 4 000 rpm.
• Transfer 1 mL supernatant into a tube containing 50 mg PSA and 50 mg C18, shake 1 min, centrifuge 3 min.
• Filter the cleaned extract through a 0.22 µm PTFE syringe filter, ready for GC-MS/MS analysis.

Instrumental Analysis (PTV-GC-MS/MS)

• GC Column: Rxi-5ms, 30 m×0.25 mm×0.25 µm.
• PTV injection: 60 °C → 300 °C (splitless 1 min, then split 20:1).
• Oven Program: 60 °C (1 min) → 20 °C/min → 180 °C → 10 °C/min → 300 °C (5 min).
• MS/MS: EI ionization, argon CID, MRM transitions for each herbicide.

Calibration, Sensitivity and Repeatability

• External calibration over 2–100 µg/L yielded correlation coefficients (R²) > 0.998 for all 13 compounds.
• Limits of detection ranged from 1.5 to 8 µg/kg in carrot matrix (S/N = 3).
• Repeatability (n = 6) for a 5 µg/L standard showed peak area RSDs < 6%.

Spike Recovery Results

• Three carrot samples spiked at 7.5 µg/kg gave average recoveries between 78% and 115% for all analytes, RSDs < 10%.

Practical Benefits

• The QuEChERS cleanup minimizes matrix effects in high-pigment carrot extract.
• PTV injection extends column life by eliminating solvent vapors.
• MRM mode ensures high selectivity and sensitivity for multi-residue analysis.
• Rapid analysis (≤ 20 min per run) boosts sample throughput for routine monitoring.

Conclusion

The combination of QuEChERS pretreatment, PTV-GC-MS/MS and MRM provides a robust, sensitive, and high-throughput method for simultaneous determination of 13 AOPP herbicides in carrot, supporting regulatory compliance and ensuring food safety.