Determination of Seven Drug Residues in Bean Sprouts by UPLC-MS/MS

A method for determination of seven drug residues (cefalexin, norfloxacin, prochloraz, 6-benzylaminourine, gibberellic acid, 4-chlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid ) in bean sprouts was established by quick, easy, cheap, effective, rugged and safe (QuEChERS) sample preparation methods， combined with ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The sample was extracted by methanol containing 0.1% formic acid through ultrasonic wave, and was purified by QuEChERS which was composed of PSA and C18, and analyzed using UPLC-MS/MS on a UPLC HSS T3 column with acetonitrile and 0.1% formic acid solution as the mobile phases in gradient elution program．The MS analysis was set in electrospray ionization mode and separated to two segments of positive and negative modes．Seven compounds were identified by retention time and the ratio of the characteristic ions, and quantitatived with external standard method. The result shows that the calibration curves are good linearity in the range of 0.4—100 μg/L with correlation coefficients more than 0.999. The method quantitation limit (MLOQ, S/N=10) of 7 compounds are 2.0—5.0 μg/kg. The average recoveries are between 80.7% and 115% at the spiked levels of 2.0—50 μg/kg, the precision (RSD, n=6) ranges from 2.6% to 13.5%. The method is simple, sensitive, and accurate, which can be applied in daily monitoring of 7 drug residues in bean sprouts.