Submitted to: Analytica Chimica Acta
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/14/2006
Publication Date: 9/19/2006
Citation: Schneider, M.J., Darwish, A.M., Freeman, D.W. 2006. Simultaneous multiresidue determination of tetracyclines and fluoroquinolones in catfish muscle using hplc with fluorescence detection. Analytica Chimica Acta. 586:269-274. Interpretive Summary: Use of antibiotics in food animals has led to concerns regarding residues which might be present in food, as well as potential increases in microbial resistance. Efficient methods are required to ensure that residues are not present in food at an unsafe level. Many methods have been developed which are designed to determine amounts of a single drug. Increasingly, methods which allow determination of multiple members of one drug class are being developed, leading to greater efficiency of analysis. We have now developed a method which allows the simultaneous analysis of multiple members of two different classes of veterinary drugs in catfish muscle, the fluoroquinolone and tetracycline antibiotics. This method involves a simple extraction of the drugs from the fish muscle, separation of the drugs by liquid chromatography, and detection of the drugs by fluorescence. Using this method, we have successfully recovered and measured levels of 3 tetracyclines and 5 fluoroquinolones from fortified fish muscle. We also were successful in measuring levels of enrofloxacin and oxytetracycline in catfish which had been dosed with one of these drugs. The increased efficiency of this approach should facilitate its use by regulatory agencies in monitoring tetracycline and fluoroquinolone antibiotics in fish muscle.
Technical Abstract: Efficient methods are needed for analysis of veterinary drug residues in food. A number of methods are available for single analytes. Multiresidue methods are now increasingly available. It is still rare, however, to find methods not involving mass spectrometry which allow for analysis of more than one class of drug residue. An efficient multiresidue method for the simultaneous determination of fluoroquinolones (FQs) and tetracyclines (TCs) in catfish muscle has now been developed. This method involves an extraction of the analytes with a mixture of acetonitrile and citrate buffer containing magnesium chloride. After centrifugation and evaporation of the supernatants, the residues are determined using HPLC with fluorescence detection. With this method, five fluoroquinolones and three tetracyclines were determined in fortified catfish muscle at levels of 20, 50, and 100 ng/g. Average recoveries for ciprofloxacin (CIP), sarafloxacin (SAR), danofloxacin (DANO), enrofloxacin (ENRO), difloxacin (DIF), oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) were in the range of 60-92% with good RSDs. The limits of quantitation ranged from 0.15 to 1.5 ng/g. Utilization of the method to successfully analyze catfish muscle samples incurred with enrofloxacin and with oxytetracycline is described.