New method for the rapid identification of tetracycline residues in foods of animal origin - using the Premi Test in combination with a metal ion chelation assay

A post-screening classification assay for tetracycline compounds has been developed and integrated into the previously reported optimized Premi Test methodology. The new post-antimicrobial screening assay is based on a metal ion chelation using calcium and sodium chloride and has been shown to be specific towards the tetracycline class. The assay is both cost-effective and complementary to the post-screening procedures that have previously been developed for the β-lactam and sulfonamide compounds. A validation study was conducted in accordance with 2002/657/EC (Commission Decision). The method is rugged and applicable to a range of tetracyclines of differing antimicrobial potencies over a wide concentration range. A blind trial was undertaken in which all antimicrobial residues in the unknown samples were successfully identified by the analyst following the integrated Premi Test procedure for the classification of antimicrobial compounds.