Abstract:Cypermethrin, a pyrethroid insecticide, is widely used due to its high efficiency and low toxicity, leading to significant residues in vegetables. However, its degradation behavior during thermal processing of vegetables remains unclear. This study developed a simultaneous high performance liquid chromatography (HPLC) method for the determination of cypermethrin and 3-phenoxybenzoic acid (3-PBA) in crown daisy to investigate the degradation of cypermethrin residues during thermal processing. The results showed that the optimal extraction conditions for cypermethrin were achieved using 0.1% acetic acid-acetonitrile as the extraction solvent, ultrasonic extraction for 15 minutes, and sample purification with 100 mg of graphitized carbon black （GCB）, resulting in recoveries between 93% and 106%. After thermal processing, blanching caused a 16.87% degradation of cypermethrin, with no 3-PBA detected, while stir-frying led to a 76.76% degradation of cypermethrin, with trace amounts of 3-PBA detected. Three degradation products were detected by mass spectrometry, and combined with theoretical calculations, the degradation pathway of cypermethrin was suggested. This study can provide a basis for the dietary exposure assessment of cypermethrin and its metabolites.
