Evaluation of solid-phase sorbents for the analysis of ropinirole in whole blood

In this paper, the extraction and analysis of ropinirole from whole blood using solid-phase cartridges is presented. Previously published methods for the analysis of this drug have employed plasma samples using C(18) cartridges. Liquid-liquid extraction has been employed for analysis of postmortem samples. In the method, drug free blood was spiked with ropinirole (0 to 10 ng) and an internal standard (quinidine). The samples were buffered with distilled water and centrifuged. The supernatant liquid was applied to previously conditioned endcapped C(6), C(18), and C(8)/SCX solid-phase extraction columns. The columns were washed, dried, and eluted with various solvents systems. The eluants were collected and evaporated. The residue was dissolved in 100 microL of aqueous 0.1% trifluoroacetic acid and analyzed by liquid chromatography using a C(18) (4.6 x 150 mm, 5-microm particle size) column and monitored at 250 nm, using diode-array detection. A mobile phase consisting of methanol/0.1% TFA in distilled water (22:78 v/v) was employed. The data was collected and appraised. It was found that 3-mL 200-mg CEC06 C6 (Hexyl endcapped) solid-phase columns that had been washed with 3 x 3 mL water and 3 x 3 mL acetonitrile and eluted with a solvent system consisting of 95:5 v/v acetonitrile/ammonia performed best. The linear range for this analysis was found to be from 0 to 10 ng/mL. The limit of detection was determined to be 1 ng/mL with a limit of quantification of 2.5 ng/mL.