A liquid chromatography-mass spectrometric method was developed and validated to determine six polyether ionophores (lasalocid sodium, monensin sodium, salinomycin sodium, narasin, maduramicin ammonium alpha and semduramicin sodium) in feed samples, reported Mervi Rokka and colleagues at the Finnish Food Safety Authority, Evira, in the journal, BioMed Research International.

The method developed was very straightforward, they report, involving extraction with 84 per cent acetonitrile of the coccidiostats from the feed samples and filtration of the raw extract prior to chromatographic analysis. Method validation included the determination of selectivity, linearity, specificity, repeatability, the limit of detection, limit of quantification, decision limit (CCΑ), detection capability (CCΒ) and recovery.

Feed samples from the Finnish national feed control programme and suspected carry-over samples from a feed manufacturer were analysed in parallel with an existing liquid chromatography method coupled with ultraviolet detection. All feed control samples were negative in LC-UV but with the developed MS method, monensin, salinomycin and narasin were detected at concentrations of <0.025–0.73mg per kg, <0.025–0.027mg per kg and <0.025–1.6mg per kg, respectively.

Rokka and colleagues also reported that, in suspected carry-over samples after an output of 2.0 tonnes of unmedicated feed in the pelleting line, the concentrations of monensin, salinomycin and narasin varied from undetected to 16mg per kg. In the mixer line, after 3.2 tonnes of unmedicated feed output, the concentrations of monensin, salinomycin, and narasin varied from undetected to 2.4mg per kg.

Reference

Rokka M., M. Jestoi and K. Peltonen. 2013. Trace level determination of polyether ionophores in feed. BioMed Research International, Volume 2013, Article ID 151363, 12 pages. dx.doi.org/10.1155/2013/151363

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February 2013