SIMULTANEOUS DETERMINATION OF 18-OXYGENATED CORTICOSTEROIDS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH FLUORESCENCE DETECTION

A method for differentially measuring the 18-oxygenated corticosteroids, 18-hydroxycortisol, 18-hydroxycortisone and 18-oxocortisol, in human urine from the patients with primary aldosteronism has been developed by high-performance liquid chromatography with fluorescence detection. The method involves the derivatization of 18-oxygenated corticosteroids into the fluorescent 21-anthroyl esters by the action with 1-anthroyl nitrile. Urine was first extracted with a mixture of ether-dichloromethane, and solid-phase extraction of the anthroyl derivatives on a Bond Elut CN cartridge column was used as a clean up step before final separation by high-performance liquid chromatography with fluorescence detection. 11,18-Epoxypredonisolone was used as an internal standard. The linearity of the calibration curve for each steroid was from 0.5 pmol to 25 pmol per injection, and the detection limit was 0.1 pmol (SN = 5).