Application of a semipermeable surface column for the determination of amoxicillin in human blood serum.

A high-performance liquid chromatography column-switching system for the automated determination of amoxicillin in human serum was developed as a more efficient alternative for the already existing systems with off-line sample pretreatment. The column-switching system consists of a semipermeable surface (SPS) column and an analytical reversed-phase (RP) C18 column. After centrifuging, pure serum samples were injected into the column-switching system. Clean-up, with regard to removal of proteins, was performed on the SPS column. The fraction containing amoxicillin was concentrated on the analytical RP-C18 column. Finally, chromatography and detection were performed with the RP-C18 column using UV detection at 234 nm. The total analysis time was 15 min. The method has proven to be reliable and to be more time- and resource-efficient compared to previously used methods with off-line sample clean-up. It is now used in bioavailability studies for the development of new amoxicillin formulations.