Determination of Clenbuterol and Chloramphenicol in Pig Urine Using Dispersive Liquid-Liquid Microextraction with High Performance Liquid Chromatography-Tandem Mass Spectrometry

KeyWord:dispersive liquid-liquid microextraction  high performance liquid chromatography-tandem mass spectrometry£¨HPLC-MS/MS£©  pig urine  clenbuterol  chloramphenicol

Abstract:

      A quick and simple analytical method was developed for the determination of clenbuterol and chloramphenicol residues in pig urine using dispersive liquid-liquid microextraction combined with high performance liquid chromatography-tandem mass spectrometry£¨HPLC-MS/MS£©.5 mL pig urine with pH adjusted to 10.0 was added with 5 ng clenbuterol-D9£¬5 ng chloramphenicol-D5 and 10% NaCl before extraction.Then the urine sample was added with the mixture of 250 ¦ÌL chloroform and 750 ¦ÌL isopropanol for dispersive liquid-liquid microextraction.After centrifugation,the sediment was transferred and dried under a gentle nitrogen flow,then redissolved with methanol-water solution.The clenbuterol and chloramphenicol in pig urine was simultaneously determined by HPLC-MS/MS under positive and negative transferring mode with the internal standard method.The spiked recoveries ranged from 82% to 97% at fortification levels of 0.05-2 ¦Ìg/L for clenbuterol and 0.1-2 ¦Ìg/L for chloramphenicol,with relative standard deviations of 6.8%-9.6%.The limits of quantitation£¨LOQs£© were 0.05 ¦Ìg/L for clenbuterol and 0.1 ¦Ìg/L for chloramphenicol,respectively.With the advantages of convinience,sensitivity,good recoveries and repeatability,the method was suitable for the detection of clenbuterol and chloramphenicol residues in pig urine.