Determination of amoxicillin in human plasma by LC-MS/MS and its application to a bioequivalence study

An analytical method based on solid phase extraction has been developed and validated for analysis of amoxicillin in human plasma using gemifloxacin as an internal standard. A COSMOSIL 5C18-PAQ column provided chromatographic separation of analytes followed by detection with mass spectrometry. The method involves simple isocratic chromatographic conditions and mass spectrometric detection in the positive ionization mode using an API-3000 system. The proposed method has been validated with linear range of 100-15000 ng/mL for amoxicillin. The intra-run and inter-run precision values are within 3.53% and 5.63% respectively for amoxicillin at LOQ level. Total elution time was as low as 2 min. This validated method was used successfully for analysis of plasma samples from a bioequivalence study.