ABSTRACT
An in vivo microdialysis sampling method coupled to high-performance liquid chromatography has been applied for continuous monitoring of unbound ampicillin in rat blood. A microdialysis probe was inserted into the jugular vein/right atrium of Sprague-Dawley rats, and doses of 100 and 200 mg/kg ampicillin were then administered via the femoral vein. Dialysates were collected and directly injected into a liquid chromatographic system. Isocratic elution of ampicillin was achieved within 10 min using the liquid chromatographic system. The chromatographic mobile phase consisted of methanol-100 mM monosodium phosphoric acid (25:75, v/v, pH 5.5). The wavelength of the UV detector was set at 230 nm. The calibration curves from 0.25 to 50 μg/ml were linear with correlation coefficients of 0.995. The method provides a simple technique for rapid analysis of unbound ampicillin in rat blood for used in pharmacokinetic study.