An analytical method was developed for the non directional screening of 34 residues in 7 categories of veterinary drugs by ultra high performance liquid chromatography-hybrid quadrupole-orbitrap mass spectrometry(UHPLC-Q-Orbitrap MS) based on mass spectrometry fragmentation.The qualitative screening of the analytes was performed by MS in a data independent acquisition mode

based on retention time

accurate mass number

secondary fragmentation information of 34 veterinary drug standard substances.The characteristic fracture fragments of 7 categories of veterinary drugs were obtained by exploring the molecular ion mass spectrometry rupture process and cracking mechanism.A method for untargeted screening of target and non target substances in deep processed lamb products was established by combining the compound database with characteristic ion fragments in the data independent collection mode.Results showed that there were good linear relationships for 34 veterinary drugs in respective concentration ranges with their correlation coefficients(r2) larger than 0.99.The limits of detection and quantitation were 0.04-4.76 μg/kg and 0.07-8.24 μg/kg

respectively.Average recoveries at three added levels ranged from 79.4% to 110%

with relative standard deviations(RSD) of 0.30%-7.5%.The method was applied in the non directional screening of veterinary drug residues in commercially available deep processed lamb samples

and difloxacin outside the standard library was also detected beside sulfamethazine.Hence

the proposed method is simple and efficient

and could be employed for accurate determination of veterinary drug residues in lamb products.