Submitted to: Association Official Analytical Chemists Annual Intrl Meeting & Exposition
Publication Type: Abstract Only
Publication Acceptance Date: 6/29/2004
Publication Date: 9/19/2004
Citation: Schneider, M.J. 2004. A rapid fluorometric screening assay for both enrofloxacin and tetracyclines in chicken muscle. Association Official Analytical Chemists Annual Intrl Meeting & Exposition.
Technical Abstract: A Rapid Fluorometric Screening Assay for Both Enrofloxacin and Tetracyclines in Chicken Muscle. The fluoroquinolone antibiotic enrofloxacin was approved for use in chickens in the U.S., with a tolerance level of 300 ng/g in muscle. Tetracyclines (tetracycline, oxytetracycline, and chlortetracycline) are currently approved for use in chickens with a tolerance level of 2 µg/g in muscle. A rapid screening assay for both enrofloxacin and the tetracyclines at their respective tolerance levels has been developed, which takes advantage of the differing fluorescence properties of these two classes of antibiotics. The procedure requires simply extraction of the tissue in acidic acetonitrile, centrifugation, and analysis of the fluorescence of the supernatant for enrofloxacin at 440 nm. Tetracyclines present in the sample do not significantly fluoresce under these acidic conditions. This supernatant is then basified with ammonium hydroxide, centrifuged, the supernatant treated with Mg+2 and centrifuged. This final supernatant is then analyzed for tetracycline fluorescence at 515 nm. Enrofloxacin in the sample does not significantly fluoresce at this wavelength. Individual control chicken breasts tested with and without fortification with chlortetracycline (2 µg/g) and enrofloxacin (300 ng/g) showed a threshold can be set for discrimination between these two types of samples for each analyte. This work provides a rapid and effective screening method for the presence of both enrofloxacin at 300 ng/g and the tetracyclines at 2 µg/g in one tissue extract.