Determination of oxytetracycline and chlortetracycline residues in eggs by HPLC

A high performance liquid chromatographic(HPLC) method was used for simultaneous determination of oxytetracycline(OTC)and chlortetracycline(CTC) residues in eggs. The OTC and CTC were extracted with (0.01) mol/L ethylenediaminetetraacetic acid disodium and 0.3% phosphoric acid. After the protein precipitation with trichloroacetic acid, the extract were purified and concentrated by passing through Bond Elut C_(18) solid-phase(extraction) cartridges. The HPLC determination was carried out on a Waters Symmetry Shield~(TM) RP_(18) column (250 mm×4.6 mm i.d., 5 μm)and oxalic acid (0.02 mol/L)-acetonitrile-sodium dihydrogenphosphate (0.01 mol/L) (45∶19∶36) as mobile phase with UV detection at 353 nm. The linear range of calibration curve were(0.05 ～1.0 μg/mL) for OTC and 0.1～2.0 μg/mL for CTC. Recoveries for OTC and CTC were between 50.6%and 85.6%, RSDs were not more than 8.60%(n=5).