Determination of amoxycillin in plasma by ion pair column extraction and reversed-phase ion pair high-performance liquid chromatography.

A quantitative method is described for the determination of amoxycillin in plasma. The method utilizes ion pair extraction of amoxycillin on disposable columns packed with Baker-10 SPE octadecyl, with tetrabutylammonium ion as the counter ion and methanol as the eluent. Separation and quantitation is performed by reversed-phase ion pair high-performance liquid chromatography (Nucleosil C-18) using the same counter ion and a mobile phase of methanol-phosphate buffer (pH 6.0) (31:69 v/v) with detection at 229 nm.