High-performance liquid chromatographic determination of chlorhexidine in whole blood by solid-phase extraction and kinetics following an intravenous infusion in rats.

This paper presents the extraction and analysis of chlorhexidine (CHX) from whole blood using solid-phase extraction (SPE) together with high-performance liquid chromatography (HPLC). Blood samples, spiked with chlorpromazine used as an internal standard, were fortified with sodium acetate buffer and purified with Bakerbond C(18) SPE columns. The columns were washed, dried, and eluted with experimental optimized solvent systems. The HPLC was performed using a Capcell Pak C(18) MG column (4.6 x 250-mm) and monitored at 260 nm, using a UV detector. A mobile phase consisting of acetonitrile/water (40:60 v/v), containing 0.05% trifluoroacetic acid, 0.05% heptafluorobutyric acid, and 0.1% triethylamine, was employed. The assay was linear over the range of 0.05 to 2.0 microg/g and the limit of detection was 0.01 microg/g for CHX in whole blood. At the concentration range of 0.05 to 2.0 microg/g, the recoveries ranged from 72% to 85%, and the intra- and interday precision, expressed as coefficient of variation, were less than 11% and 13%, respectively. Kinetic characteristics following an intravenous infusion of a CHX product, Maskin solution, at a dose of 15 mg/kg in rats were evaluated using the present method. The kinetic profiles of CHX conformed to a two-compartment model with an alpha half-life (of distribution) at 0.05 h and a beta half-life (of elimination) at 0.55 h in rats. The method is simple and reliable for the determination of CHX in blood samples and could be expected to apply to forensic and clinical specimens.