Objective To establish a high performance liquid chromatographic method for the determination of micro-amount of
ivermectin
in pig serum. Methods
Ivermectin in pig serum was extracted with ethyl acetate after the serum protein was precipitated with 0.05% metaphosphoric acid-
methanol in the ratio of 7∶3(V/V). Then the sample was centrifuged at 4000 r/min for 5 min and the supernate was evaporated to dryness with rotary vacuum evaporator. The residue was dissolved with 0.20 ml of methanol as the sample solution for HPLC analysis. HPLC column used was a phenomenex ○R C18(5 μm, 250 mm×4.6 mm) with a same type of guard column. Mobile phase consisted of methanol and water in the ratio of 90∶10(V/V) and the flow rate was 1.0 ml/min. The detection wavelength was 245 nm. Results The linear range of the method was found to be 0.010-20 mg/L and its detection limit was 0.010 mg/L. The relative standard deviation of the method was 0.78%-3.82% and the recoveries varied from 94.0% to 100.0%, with an average recovery of 97.3%. Conclusion This method is simple, reproducible, accurate and suitable to the determination of micro-amount of ivermectin in pig serum.