A method for determining amoxicillin in human plasma by ESI-LC-MS/MS and using cephalexin as an internal standard was validated. The chromatographic separation was performed in a C18 Shim-pack CLC-ODS(M) analytical column (150 mm x 4.6 mm i.d. x 5 μm), which provided satisfactory separation of amoxicillin and cephalexin peaks, with analysis time of 3.1 minutes. A yield of extraction of 96.6% fo...
