SIMULTANEOUS DETERMINATION OF CARBADOX AN D OXYTETRACYCLINE IN SWINE TISSUES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A simple, rapid and reliable high performance liquid chromatographic ( HPLC) method for the simultaneous determination of carbadox and oxytet racycline in swine muscle and liver has been developed. The drugs were extracted with 0.3% metaphosphoric acid-methanol (7: 3), followed by a Bond Elut C-18 clean-up procedure. The HPLC separation was carried o ut on a Wakosil-II 5C18 RS column (150 x 4.6 mm i. d.) with 0.05 M sod ium dihydrogenphosphate (pH 4.5)-acetonitrile (87:13) as the mobile ph ase at the flow-rate of 1.0 ml/min. The drugs were detected by UV abso rbance measurement at 360 nm. The calibration graphs were rectilinear from 0.1 to 50 ng for carbadox, and from 1 to 50 ng for oxytetracyclin e. The recoveries of the drugs from swine muscle and liver fortified a t the level of 0.1 mu g/g were 83.7-185.6%, with high precision. The l imits of detection were 0.002 mu g/g for carbadox and 0.05 mu g/g for oxytetracycline in swine muscle. The accuracy and reproducibility of t he present method were sufficient for residue analysis.