Multi-residue method development of 8 benzoylurea insecticides in mandarin and apple using high performance liquid chromatography and liquid chromatography-tandem mass spectrometry

Multi-residue method of eight benzoylurea insecticdes (8BUs; diflubenzuron, triflumuron, hexaflumuron, teflubenzuron, novaluron, lufenuron, flufenoxuron, and chlorfluazuron) in apple and mandarin were developed with high performance liquid chromatography and liquid chromatography-tandem Mass spectrometry. Using multiresidue standard solutions, extraction, partition, and clean-up procedures have been established. Extraction with acetone and partition with n-hexane gave reasonable recovery of more than 90%. Clean-up with florisil-glass column using acetone/n-hexane as eluting solvents resulted in good efficiency of higher than 94%. By employing the established analytical method, recovery test of 8BUs in mandarin and apple was conducted to give recovery of 80–110%, which satisfies the Korea Food & Drug Administration criteria. The method limit of quantitation (MLOQ, 0.02 mg/kg) was lower than 1/2 of maximum residue limits of crops. Excellent sensitivity and selectivity were obtained with liquid chromatography tandem mass spectrometry (LC-MS/MS)-Electrospray ionization(-) even in the samples with no clean-up, suggesting LC-MS/MS can be used for the fast multi-residue method of 8 benzoylurea insecticides in mandarin and apple.