DETERMINATION OF AMOXICILLIN IN HUMAN PLASMA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND SOLID-PHASE EXTRACTION

A high-performance liquid chromatographic method using solid phase extraction has been developed for the determination of amoxicillin in human plasma. After concentration of amoxicillin on a C-8 cartridge, the cartridge was eluted on-line to a reversed-phase column packed with 5 mum Chromspher C18. The mobile phase was methanol-0.08 M phosphate buffer (pH 7.6) (20:80), which contained 0.01 M tetrabutylammonium dihydrogenphosphate. The column effluent was monitored by UV spectrophotometry at 234 nm. The method has proved to be reliable and is used in bioavailability studies for the development of new amoxicillin formulations.