| 【Objective】The study was aimed to establish a HPLC method for the determination of amoxicillin,
ampicillin, penicillin G, penicillin V, oxacillin, cloxacillin, and dicloxicillin in feeds.【Method】Firstly, the samples of
formula feed, concentrated feed and concentrate supplement were extracted with 20% acetonitrile solution, and the premixed
feed samples were extracted by EDTA-Mcllvaine buffer solution and purified by HLB solid-phase extraction column, and
then derivated by the reagents. Eventually, the samples were separated on a C18（150 mm×4.6 mm, i.d 5 μm）column by
gradient elution with acetonitrile - phosphate buffer solution as mobile phase, detected by UV detecor at 325 nm, calibrated
by matrix matching standard working solution and quantified by external standard method.【Result】There were good linear
relationships among the seven kinds of penicillins of formula feed, concentrated feed and concentrate supplement in the
concentration range of 0.25-10 μg/mL, and there were good relationships among the seven kinds of penicillins of premixed additive feed in the concentration range of 0.10-10μg/mL. The average recovery rates were in the range of 69.6%-103.7% with
RSD value less than 15%. The limit of detection（LOD）of compound feed, concentrated feed and concentrate supplement
was 2.5 mg/kg , and the limit of quantification（LOQ）was 5 mg/kg. The LOD of premixed additive feed was 1.0 mg/kg and the
LOQ was 2.0 mg/kg.【Conclusion】The method was proved to be specific, rapid, accurate and reproducible for determination of
seven penicillin antibiotics in daily feed . |
