Simultaneous determination of lincomycin, spiramycin, tylosin and tiamulin in animal feed using liquid chromatography coupled to mass spectrometry after a microbial assay.

INTRODUCTION: To monitor the occurrence of antibiotics in feed, a two-step control strategy is often adopted of screening by microbiological inhibition followed by confirmation by chromatographic techniques. This study is devoted to the development of a reliable method for simultaneous determination of lincomycin, spiramycin, tylosin and tiamulin in animal feed using liquid chromatography coupled to mass spectrometry after a microbial assay.

MATERIAL AND METHODS: The analytes were extracted from feed using a methanol:water mixture, and solid-phase extraction was employed for the isolation of the antibiotics. The determination of the presence of lincomycin, spiramycin, tylosin and tiamulin was carried out using high-performance liquid chromatography with mass spectrometry.

RESULTS: The method was validated according to EU requirements. The decision limit and detection capability were 0.213-0.318 and 0.259-0.535 mg kg-1, respectively, and the limits of detection and quantification were 0.029-0.151 and 0.069-0.223 mg kg-1, respectively, depending on the analyte. Recoveries were satisfactory (86.6-105.1%), repeatability ranged from 2.6 to 18.3% and reproducibility from 6.2 to 11.7%.

CONCLUSION: The proposed method is reliable and applicable to identify four antibiotics for feed-safety control.