Tetracycline residues in meat and bone meals.: Part 1:: Methodology and examination of field samples

The incidence of tetracycline residues in commercially available samples of meat meals and meat and bone meals was investigated. Four different methods were used on each of the 87 samples from nine different rendering plants in Germany: examination using a screening fluorescence test: examination by high performance liquid chromatography analysis using three different extraction procedures (succinate buffer, hydrochloric acid, hydrochloric acid after sedimentation of bone particles). Tetracyclines were found in 100% of the samples by one or more of the extraction procedures. The highest concentrations found in meat meals were 2048 mug kg(-1), 1393 mug kg(-1) and 608 mug kg(-1) for oxytetracycline, tetracycline and chlortetracycline, respectively. In meat and bone meals the highest concentrations were 2295 mug oxytetracycline kg(-1), 848 mug tetracycline kg(-1) and 1274 mug chlortetracycline kg(-1). The extraction after sedimentation was the most effective of the applied extraction procedures and exposed the highest total tetracycline concentrations. The results of this investigation showed that considerable amounts of tetracyclines have to be expected in field samples. Further research has to be done on the heat stability of bound tetracycline residues.