Studies on the Determination of Clenbuterol and Ractopamine in Swine Hairs by HPLC-MS/MS and Their Residue Elimination

A method for simultaneous determination of clenbuterol and ractopamine residues in swine hairs was developed using high performance liquid chromatography coupled with tandem mass spectrometry.After hydrolyzed by 1 mol/L sodium hydroxide aqueous solution,extracted by ethyl aetate,purified by MCX solid phase extraction cartridge,the sample was dissolved in mobile phase for analysis by HPLC-MS/MS.The calibration curve of clenbuterol was linear in the range of 1.9～463.2 ng/mL(R2=0.999 0),the recoveries of different quantities of clenbuterol in swine hairs were from 83.3% to 86.6% with RSD from 6.7% to 9.2%.The limit of determination and limit of quantitative of clenbuterol were 0.4 μg/kg and 0.8 μg/kg,respectively.The calibration curve of ractopamine was linear in the range of 2.8～562.9 ng/mL(R2=0.999 2),the recoveries of different quantities of ractopamine in swine hairs were from 83.4% to 88.4% with RSD from 7.2% to 9.6%.The limit of determination and limit of quantitative of ractopamine were 0.4 μg/kg and 1.2 μg/kg,respectively.The result indicated that the residues of clenbuterol and ractopamine were found in swine hairs from the seventh day that the swines were fed with these drugs to the 21st day that the swines had not been fed;25 copy of swine hair samples were determined by the method,the residue of clenbuterol was found in one of these samples,its content was 58.68 μg/kg.