The measurement of propofol in human blood samples by liquid chromatography

A simple, sensitive, reliable and rapid column liquid chromatographic method was developed for the measurement of propofol, a new anesthetic agent, in human maternal and placental blood. The assay involved a single extraction of the drug and internal standard, thymol, from blood buffered with 0.1 M sodium dihydrogen phosphate buffer into cyclohexane. The organic extract, basified with tetramethylammonium hydroxide, in evaporation tube was evaporated to dryness at 30 degrees C under nitrogen. The residue was redissolved in 80 microliters acetonitrile and an aliquot (25-50 microliters) of the concentrate was injected into a C18 reversed-phase column (4 microns, Nova-Pak) linked to a C18 pre-column. The mobile phase consisted of 60% (v/v) acetonitrile in distilled water containing 1% v/v glacial acetic acid and was eluted at 2.5 ml min-1. The components of the column effluent was monitored by a fluorometric detector with excitation and emission wavelengths set at 276 nm and 310 nm, respectively. The method has been used to measure propofol concentrations in blood from maternal veins and placental arteries and veins during cesarean section.