Animal feeding stuffs: Methods of sampling and analysis - Screening on the antibiotics tylosin, virginiamycin, spiramycin, bacitracin-zinc and avoparcin at sub-additive levels in compound feed by a microbiological plate test
This European Standard presents a method describing the screening on the antibiotics tylosin, virginiamycin, spiramycin, bacitracin-zinc and avoparcin at sub-additive levels in complete feeding stuffs and milk replacers by a microbiological 3-plate test.The limit of detection of the method is 1 mg/ kg for avoparcin, tylosin, spiramycin and virginiamycin, and 5 mg/ kg for zinc bacitracin. The presence of other (veterinary) antibiotics may interfere with the method.Furthermore, high concentrations of metals (Cu, Zn) may interfere. The method should be used as a qualitative screening method. Positive results can be analysed further by TLC for confirmatory purposes LC-MS is required [1].A lower limit of detection for zinc bacitracin (3 mg/ kg) is achievable (see Table 2), but should be established with an in house validation first.
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