Abstract: An ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method was developed for the simultaneous determination of 29 veterinary drugs of quinolones, sulfonamides, macrolides and nitrofurans in compound feeds. The sample was extracted with methanol-acetonitrile (1:1, v/v), and then cleaned up using solid phase extraction with an Oasis HLB column, detected by UPLC-ESI-MS/MS. The UPLC separation was performed on a C18 column (100 mm×2.1 mm, 1.7 μm) using a gradient elution with the mobile phases of methanol and 0.1% (v/v) formic acid aqueous solution. The ESI-MS/MS detection was achieved in positive mode under multiple reaction monitoring (MRM) mode. The linear ranges were from 0.01 to 5.0 mg/L with the correlation coefficients above 0.99 for all the 29 veterinary drugs. The average recoveries of the 29 veterinary drugs spiked in three feed matrixes (the compound premix feed, the complete formula feed and the concentrated feed) at four spiked levels were 61.2%~94.3% with the relative standard deviations (RSDs) of 2.2%~15.0%. The limits of detection were 0.01 mg/kg or 0.05 mg/kg. The method is rapid, accurate, reproducible, sensitive and easy to apply, and suitable for the simultaneous determination of diverse veterinary drugs in compound feeds.

Key words: compound feeds, veterinary drugs, ultra performance liquid chromatography-electrospray ionization tandem quadrupole mass spectrometry (UPLC-ESI-MS/MS)