Validation of the eta-s.t.a.r. 1+1 for rapid screening of residues of -lactam antibiotics in milk

摘要

The 2-min protocol (1 + 1) for the eta-s.t.a.r. (manufactured by Neogen Corporation, Lansing, MI, USA) was validated at the Technology and Food Science Unit of the Institute for Agricultural and Fisheries Research according to Commission Decision 2002/657/EC. The test was very selective for the group of -lactam compounds: the only interference found was by clavulanic acid at 2500 mu g kg-1 and above. The modified protocol (eta-s.t.a.r. 1 + 1) detected all -lactams with a maximum residue limit (MRL) in milk, but not all these compounds were detected at their respective MRL. The detection of cefalexin (detection capability = 6000 mu g kg-1; MRL = 100 mu g kg-1) and penethamate (detection capability = 80 mu g kg-1; MRL = 4 mu g kg-1) was especially poor, and also ceftiofur was only detected from 500 mu g kg-1 (MRL = 100 mu g kg-1). The repeatability of the reader and of the test was very good. The test was very robust: test results were not significantly influenced by small changes in the test protocol, by the milk composition or by the type of milk. The test was also suitable to test the milk of animal species other than cow. Favourable results were obtained in testing monitoring samples, in two national ring trials, and in an international proficiency test. The eta-s.t.a.r. 1 + 1 is a very fast, simple, and reliable test that could be used at the farm level to prevent tanker milk contamination by -lactams.