Simultaneous Determination of Fourteen Veterinary Antibiotics in Animal Feces by Solid Phase Extraction and High Performance Liquid Chromatography

An efficient method for simultaneous determination of 14 veterinary antibiotics in animal feces by high-performance liquid chromatography was established under optimizing pretreatment and detection conditions. The results showed that 14 drugs could be separated thoroughly by 1% of acetic acid solution (pH 2.6) and acetonitrile. The detection limits for tetracyclines (TCs), sulfonamides (SAs), fluoroquinolones (FQs) and tylosin (TYL) were 35-90 mu g kg(-1), 12-28 mu g kg(-1), 9-17 mu g kg(-1) and 19 mu g kg(-1), respectively (the signal-to-noise ratio was 3). After being extracted with a mixture of 50% methanol and 50% buffer solution, enriched and cleaned-up by hydrophi-liclipophilic balanced cartage (HLB), the corresponding recoveries were 58%-75%, 74%-93%, 74%-80% and 85% at a concentration of 1 mg kg-1 and were 66%-83%, 91%-101%, 80%-88% and 68% at a concentration of 10 mg kg(-1), respectively. The method was used to analyze the 14 antibiotics in samples of pig, chicken and dairy cow feces, which had been collected from concentrated animal feeding operations in Liaoning province. These drugs were observed in the range 0.75-22.34 mg kg(-1) for TCs, 0.10-1.71 mg kg(-1) for SAs, 0.38-4.46 mg kg(-1) for FQs and 0.23-0.35 mg kg(-1) for TYL.