Determination of U-89968E, a 5HT(1a) agonist in rat plasma using solid-phase extraction, precolumn derivatization and reversed-phase high-performance liquid chromatography

A selective and sensitive HPLC method was developed for the determination of U-39968E in rat plasma. The assay involved solid-phase extraction of the analyte and the internal standard and precolumn derivatization with cyclohexane-1,3-dione reagent before injection on to the HPLC column. The samples were chromatographed on a Spherisorb S5 CN column (25 cm x 4.6 mm i.d.) with a mobile phase containing acetonitrile-trifluoroacetic acid-water (17:0.2:83, v/v/v) at a flow rate of 1.5 mi min(-1). The column eluent was monitored by flourescence detection with excitation at 272 nm and emission at 320 nm. The assay is linear over the range 4-759 ng mi(-1). The relative standard deviation at the limit of quantification, 4 ng ml(-1), was 7.1%. This method was successfully applied to the determination of U-89968E in rat plasma during pharmacokinetic studies.