Determination of nine sulfonamide residues in pork and pig liver by high performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of nine sulfonamide residues in pork and pig liver.The analytes were extracted from samples using 10% sodium solution and acetonitrile/chloroform(V/V,10:1),defatted by acetonitrile-saturated n-hexane and purified by dispersion solid phase extraction using ODS C18-N and PSA as solidphase,then analyzed by HPLC/MS/MS with multiple-reaction monitoring(MRM) under positive ion mode of electrospray ionization(ESI).All the analytes were quantified by the internal standard.The limits of detection were from 0.1 μg /kg to 0.8 μg /kg.At the spiked levels of 5,10,20 μg /kg,the fortified recoveries were 74.1% ～115.8%,respectively,with relative standard deviations(RSD) less than 6.2%.