Simultaneous determination of amoxicillin and ampicillin in feed by liquid chromatography with fluorescence detection

The study was to develop a high performance liquid chromatography (HPLC) method for determination of amoxicillin and ampicillin in feeds. Fluorescence detector was set at excitation wavelength of 358 nm and emission wavelength of 440 nm. A SymmetryShield® column (RP8, 5 μm, 4.6 × 250 mm I.D.) with a mobile phase consisting of 0.01 M potassium dihydrogen phosphate (pH 2.5)：acetonitrile (82: 18, v/v) was used. The average recoveries of amoxicillin and ampicillin from spiked samples were 93.28 – 102.69 % and 88.35 – 106.14 % with repeatabilities below 4 % R.S.D.. The limits of detection of amoxicillin and ampicillin were 0.3536 and 0.0269 mg/kg, the limits of quantitation were 1.1787 and 0.0896 mg/kg for feed, respectively. Not only the method of validation was performed, but also specificity, reproducibility, precision and accuracy were confirmed. This assay has been applied to the measurement of amoxicillin and ampicillin in feeds.