Biotin-avidin mediated competitive enzyme-linked immunosorbent assay to detect residues of tetracyclines in milk

Tetracycline (TC) antibiotics are widely used for prevention and control of disease because they inhibit the growth of bacteria. However, the presence of TC antibiotics residues in food causes harmful effects on consumer's health such as allergic reactions, liver damage and gastrointestinal disturbance, so that many countries have set MRLs (maximum residue levels). Therefore, it is necessary to detect tetracycline residues, to develop suitable analytical techniques to be used as routine screens and field detection. A new approach to the biotin-avidin mediated competitive ELISA is developed to determine tetracycline residues in milk. After optimization, the LOD and LOQ were 1.0 x 10(-10) M (0.048 mu g/L) and 1.0 x 10(-9) M, respectively, and the working range from 3.16 x 10(-10) M to 3.16 x 10(-7) M toward TC in milk. No cross-reactivity was observed with the structurally similar compounds; chlortetracycline (13.7%), oxytetracycline (10%) and doxytetracycline (<1%). Additionally percent recoveries of TC spiked in milk were quite satisfactory (similar to 90%). Comparing our results obtained in this work with others, it shows with the capability to detect TC ranging in MRLs (100 mu g/L in milk) sufficiently with highly sensitivity in milk, and with simple pre-treatment. In addition, this method can apply to developing useful ELISA test kit for determination of TCs in milk. (C) 2007 Elsevier B.V. All rights reserved.