Simultaneous determination of tilmicosin,tylosin and spiramycin residues in milk by HPLC

A reliable and sensitive high-performance liquid chromatographic(HPLC) method was developed for the simultaneous determination of tilmicosin,tylosin and spiramycin residues in milk.The method used SCX SPE column as clean-up column and reversed-phase column of ZORBAX Eclipse XDB C18(5 μm,150 mm×4.6 mm i.d.) as analysis column.The extraction solution was methanol and the mobile phase was acetonitrile-0.05 mol/L phosphate buffer(pH 2.6) with gradient elution,the flow rate was 1.0 mL/min.The detection wavelength was 285 nm for tilmicosin and tylosin,232 nm for spiramycin,and the injection volume was 100 μL.The limits of detection were 30、 20 and 40 μg/kg,respectively.The linear plots were obtained between 20 and 800 μg/kg.Overall recoveries were between 88.8% and 99.4% with RSD(n=5) values between 2.2% and 8.9%.The method was sensitive,accurate,convenient and rapid,which can be used to simultaneously detect tilmicosin,tylosin and spiramycin residues in milk.