JRC-IRMM has released two new reference materials which will enable food-testing laboratories to reliably detect and quantify oxytetracycline in milk.
Oxytetracycline is a broad-spectrum antibiotic and highly effective against many pathogenic bacteria and widely used in lactating and non-lactating dairy cattle for treatment of bacterial infections such as enteritis, pneumonia, and diphtheria. However, to protect consumers from possible adverse side effects, a maximum residue limit (MRL) of 100 μg OTC/kg milk has been stipulated in EU legislation (Commission Regulation No. 508/1999).
A set of two certified reference material is now available: oxytetracycline in partially skimmed milk (ERM-BB492) and partially skimmed milk blank material (ERM-BB493). Spray-dried milk powder was chosen for the matrix format, as it best meets the stability requirements while assuring good reconstituteability.
The reference materials are intended to be used for method validation purposes (trueness estimation) and method performance control. The certified value for ERM-BB492 is 101 ± 11 μg/kg (mean ± expanded uncertainty, k=2) and is based on an inter-laboratory characterisation study; the uncertainty value contains contributions from the characterisation study, the common calibrant, and the homogeneity and stability assessment. For ERM-BB493, the certified value was established as '< 5 µg/kg' and corresponds to the LOQ of the most sensitive method in the intercomparison. Both values are traceable to the International System of Units (SI). The material has been processed and certified in accordance to ISO Guides 34 and 35. Details about material processing and certification are described in detail in the certification report.