Determination of Six Pyrethroid Insecticides in Food Crops by Multi-gradient HPLC-DAD

A high performance liquid chromatography (HPLC) - diode array detector (DAD) method with multi-gradients was developed to determine six pyrethroid insecticides in food crops, including tetramethrin, cyhalothrin, beta-cypermethrin, dimefluthrin, fenvalerate and bifenthrin samples. After samples were extracted with methanol, under using solvent gradient and velocity gradient combined with extracting maximum absorption wavelength of the studied analytes within detection wavelength range of 200-300 nm, the six insecticides were separated and detected using C18 column and DAD with methanol and water as mobile phase. The results showed that complete separation of the six pyrethroid insecticides was achieved within 18.5 min. Good linear correlation coefficients were obtained from 0.9984 to 1.0000. The average spiked recoveries were in range of 82.1%-94.9%. The limits of detection ranging from 0.01 to 0.05 μg/mL are sufficient to analyze pyrethroid residues, and the relative standard deviations (RSDs) were in the range of 1.47%-3.83% (n=5). The proposed method was simple, high-efficient and can be used to determine pyrethriods in food crops.