An analytical method was developed for the simultaneous determination of kasugamycin and benziothiazolinone residues in citrus by dispersive solid phase extraction/ultra performance liquid chromatography-tandem mass spectrometry(DSPE/UPLC-MS/MS).Citrus whole fruit and pulp were extracted with acetonitrile containing 0.5% formic acid and 0.5% aqueous ammonia-water(7∶3

by volume)

respectively

then purified with octadecyl silica gel(C18) and separated on a Waters ACQUITY UPLC HSS T3 column by gradient elution with 0.2% aqueous formic acid-methanol as mobile phase

finally analyzed in multiple reaction monitoring(MRM) mode and quantified by matrix matched standard curve external standard method.Results showed that there were good linear relationships for the target compounds in the range of 0.5-200 μg/L with their correlation coefficients(r2) larger than 0.999.The limits of detection(LODs) and the limits of quantitation(LOQs) were in the concentration ranges of 0.006-0.04 μg/kg and 5-10 μg/kg

respectively.The spiked recoveries ranged from 73.4% to 104% with relative standard deviations(RSDs

n=6) of 1.6%-96%.With easy operation and high sensitivity

the method is suitable for the simultaneous determination of kasugamycin and benziothiazolinone residues in citrus.