Author
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MOATS, WILLIAM - 1265-70-00 (RETIRED) |
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Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/28/2000 Publication Date: N/A Citation: N/A Interpretive Summary: The tetracycline group of antibiotics including chlortetracycline, tetracycline, and oxytetracycline is widely used for treatment of farm animals. These uses can result in residues in the tissues of treated animals. Some countries have very strict regulations with regard to the presence of residues of the tetracycline group of antibiotics in animal products. There are some reports that shipments of pork from the United States to other countries have been rejected because of the alleged presence of residues of tetracycline antibiotics. There is, therefore, a need for simple and rapid chromatographic methods to establish the presence or absence of these compounds. Many procedures have been described for liquid chromatographic (LC) determination of tetracycline antibiotic residues in tissues. Most require lengthy sample preparation procedures which result in low and variable recoveries. Some LC columns do not work well with tetracycline antibiotics. This paper describes an innovative approach which eliminates the need for lengthy sample preparation. New types of LC columns were also evaluated. The new procedure is thus simpler and more accurate. Technical Abstract: A simplified procedure was developed for determination of tetracycline antibiotics in tissues, which improved stability of these compounds in sample extracts and to eliminate the need for troublesome cleanup procedures. Tissues were homogenized in water. Acetonitrile (16 mL) and then 1 mL of 0.1 M H3PO4 were added to 4 mL of homogenate and the clear supernatant was filtered. The filtrate was mixed with hexane and dichloromethane and the resulting water layer was collected, evaporated to 1-2 mL and filtered into autosampler vials. Ion-pairing liquid chromatography was used to separate tetracyclines from interferences in sample extracts, eliminating the need for further cleanup. Analysis was isocratic using a Phenomonex Prodigy ODS(3) column with a mobile-phase of 0.16 M KH2PO4, 0.04 M H3PO4, 0.01 M sodium decanesulfonate (68+32 for oxytetracycline and tetracycline; 64+36 for chlortetracycline). Recoveries were generally in the 90-100 percent range with limits of quantitation of 0.05-0.1 ppm. The procedure was evaluated with beef and pork muscle, liver, and kidney. |
