Liquid chromatographic determination of oxytetracycline in swine tissues

A simple and rapid method was developed for determination of oxytetracycline (OTC) in swine muscle and kidney by liquid chromatography (LC). The method involved homogenization of sample in acetonitrile-1M imidazole buffer containing 10 mM disodium ethylenediaminetetraacetic acid (Na2.EDTA) and 50 mM magnesium acetate (15 + 85) with added hexane, centrifugation, removal of the hexane phase, and ultrafiltration of the supernatant. L-column ODS (150 x 4.6 mm) with a mobile phase of acetonitrile-1M imidazole buffer containing 50 mM magnesium acetate and 10 mM Na2.EDTA (10 + 90) was used for the LC separation. A fluorescence detector was used at an excitation wavelength of 380 nm and an emission wavelength of 520 nm. The calibration graph was linear from 1.25 to 200 ng OTC. Recoveries of OTC from swine tissue fortified at levels of 0.05-1.0 microgram/g ranged from 58.0 to 67.3%. The quantitation and detection limits were 0.05 and 0.04 microgram/g, respectively.