APPLICATION OF REVERSED-PHASE LIQUID-CHROMATOGRAPHY AND PREPACKED C-18 CARTRIDGES FOR THE ANALYSIS OF OXYTETRACYCLINE AND RELATED-COMPOUNDS

The reversed-phase (RP) chromatographic separation of oxytetracycline (OTC) 4-epioxytetracycline (4-epiOTC), alpha-apooxytetracycline (alpha -apoOTC), and beta-apooxytetracycline (beta-apoOTC) has been accomplis hed on an Inertsil C-8 column at ambient temperature; Using the simple x method of solvent optimization, a 0.1 M ammonium acetate buffer (pH 3.0)-acetonitrile-tetrahydrofuran (72.5:12.5:15, v/v/v) mobile phase w as found to give excellent separation of the compounds. OTC, 4-epiOTC, alpha-apoOTC and beta-apoOTC were resolved in 35 min with calculated detection limits of 40, 20, 50 and 140 ng/ml, respectively. Solid-phas e extraction (using RP C-18 cartridges) of OTC and OTC degradation com pounds from distilled water and porcine muscle was tested at four conc entration levels ranging from 200 to 2000 ng/ml (g); overall mean reco very of OTC from distilled water and porcine tissue was greater than 9 0% and 70%, respectively.