Determination of six polyether antibiotic residues in foods of animal origin by solid phase extraction combined with liquid chromatography–tandem mass spectrometry

• A method for extracting and analyzing six polyether ionophores in milk, chicken, chicken liver and egg samples was developed.
• Several clean-up strategies were tested, resulting in the use of the ENVI-Carb cartridge as the best clean-up method for all matrices.
• The method is suitable for quantitative analysis of polyether antibiotic residues in foods of animal origin with simple sample preparation.

A new method using solid phase extraction (SPE) combined with liquid chromatography–tandem mass spectrometry (LC–MS/MS) has been developed for the determination of six polyether antibiotics, including lasalocid, salinomycin, monensin, narasin, madubamycin and nigericin residues, in foods of animal origin. The samples were extracted with acetonitrile and purified by ENVI-Carb SPE columns after comparing the impurity effect and maneuverability of several SPE cartridges. Subsequently, the analytes were separated on a Hypersil Gold column (2.1 × 150 mm, 5 μm) and analyzed by MS/MS detection. The limit of quantization (LOQ) for milk and chicken was 0.4 μg/kg, and for chicken livers and eggs, it was 1 μg/kg. The linearity was satisfactory with a correlation coefficient of >0.9995 at concentrations ranging from 2 to 100 μg/L. The average recoveries of the analytes fortified at three levels ranged from 68.2 to 114.3%, and the relative standard deviations ranged from 4.5 to 12.1%. The method was suitable for quantitative analysis and confirmation of polyether antibiotic residues in foods of animal origin.