Rapid determination of amoxicillin in porcine tissues by UPLC-MS/MS with internal standard

A rapid, simple and reliable method using amoxicillin-D4 as internal standard (IS) for determination of amoxicillin (AMO) in porcine tissues was developed. The analytical methodology used a phosphate buffer (0.01 M, pH = 6.3) with trichloroacetic acid (50 mg/mL) for extraction and Oasis® HLB cartridges for clean-up followed by UPLC-MS/MS analysis. The optimized method was validated according to EU guideline 2002/657/EC and FDA guideline. The LOQ in muscle, fat, liver and kidney were set to 10 μg/kg which was below the maximum residue limits, while the LOD were set to 5 μg/kg. Results showed that using AMO-D4 as IS can effectively eliminate relative matrix interference and improve the recovery and precision. A good linearity was observed at the range of 10−500 μg/kg with a correlation coefficients (R 2 ) larger than 0.99. The mean recoveries were higher than 87.0 %, and the RSDs were lower than 11.2 %. This method could be applied to conveniently analysis the residue of AMO in different porcine tissues.