| A liquid chromatography-quadrupole/time-of-flight mass spectrometric(LC-TOF/MS) method was developed for the determination of 36 forbidden substances,belonging to β-agonists and anabolic hormones in feeds based on liquid chromatography-quadrupole/time-of-flight mass-spectrometry (LC-TOF/MS).Acetonitrile and mixed sorbents were added to the homogeneous feeds sample,and then followed by the processing steps,involved vortexing dispersion,shaking extraction,centrifugation and concentration(namely the modified QuEChERS method).The total analytes were rapidly extracted and purified.The extract was separated on a C18 column(150 mm×2.1 mm,2.7 μm) using methanol-0.1% formic acid as mobile phase by gradient elution,and analyzed under ESI positive ionization mode.Full scan experiments(TOF/MS ＆ Product ion) were performed over the m/z range of 100-1 000 Da.The quantitative analysis was carried out by extracting peak area with accurate mass.The confirmatory analysis of target compounds was performed with the qualitative fragments and retention time.Under the optimal conditions,a good separation and high sensitivity analysis of 36 substances were obtained with absolute value mass error below 7.3.The calibration curves were linear in the range of 10.0-200.0 μg/kg with correlation coefficients more than 0.99.The average recoveries at three spiked levels were in the range of 65%-120% with relative standard deviations (RSDs) no more than 24%.The proposed method was convenient,reliable and simple,and was suitable for the high-throughput and rapid screening analysis of forbidden drugs in feeds. |