1982 Volume 23 Issue 3 Pages 259-264_1
Analytical methods for residual tetracyclines (TCs) in the liver of swine are discussed.
Oxytetracycline (OTC) and chlortetracycline (CTC) were well extracted with 0.1% citric acid-ethyl alcohol (7:3) mixture, then absorbed on an Amberlite XAD-2 resin column and eluted with methyl alcohol. The eluate was concentrated to dryness and dissolved in phosphate buffer (pH 4.5) to prepare a test solution. The cup plating method with Bacillus cereus var. mycoides as the test organism was employed for the assay, and the average recoveries were 92.0% (OTC) and 84.0% (CTC). As little as 0.05μg/g (OTC) or 0.01μg/g (CTC) was detectable.
The extraction and the column chromatography were carried out on samples spiked with other antibiotics in order to check the specificity of the present method. Kanamycin (5.0μg/g), tylosin (5.0μg/g), kitasamycin (5.0μg/g) or flavophospholipol (5.0μg/g) showed no inhibition zone when the final test solution was tested by the cup plating method, but penicillin G (0.03u/g), bacitracin (0.5u/g) or monensin (0.25μg/g) showed an inhibition zone.
Bioautography was suitable for both separation and confirmation of the identity of TCs.
