LC-MS/MS measurement of ampicillin residue in swine tissues at 5 days after in-feed administration

We assessed ampicillin (ABPC) concentrations of kidney, muscle and intestineafter a 5–day withdrawal period in 2 male and a female young Large White pigs fed the dietcontaining ABPC (ABPC medicated feed, 24 mg/kg/day) for a week. The ABPC residues weremeasured with liquid chromatography–tandem mass spectrometry, and the mean recoveries andquantitation limits ranged from 91.8 to 97.2% and from 0.1 to 0.12 ng/g,respectively. The residual ABPC concentrations were ≤1.18 ng/g for themuscle, ≤0.53 ng/g for the kidney and ≤1.93 ng/g for theintestine, suggesting below the Japanese provisional maximum residue limits. These resultsreveal that the analytical method is developed for residual ABPC and that the withdrawalperiod is appropriate.