| Abstract: | Tetracyclines are extensively used in veterinary medicine. For the detection of tetracycline residues in animal products, a broad array of methods is available. Luminescent bacterial biosensors represent an attractive inexpensive, simple and fast method for screening large numbers of samples. A previously developed cell-biosensor method was subjected to an evaluation study using over 300 routine poultry samples and the results were compared with a microbial inhibition test. The cell-biosensor assay yielded many more suspect samples, 10.2% versus 2% with the inhibition test, which all could be confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Only one sample contained a concentration above the maximum residue limit (MRL) of 100 µg kg?1, while residue levels in most of the suspect samples were very low (<10 µg kg?1). The method appeared to be specific and robust. Using an experimental set-up comprising the analysis of a series of three sample dilutions allowed an appropriate cut-off for confirmatory analysis, limiting the number of samples and requiring further analysis to a minimum. |
