Direct determination of tramadol glucuronides in human urine by high-performance liquid chromatography with fluorescence detection.

A sensitive and selective reversed-phase high-performance liquid chromatography method has been developed for the direct determination of three glucuronides of the centrally acting analgesic tramadol (1). Separation of these glucuronides into their diastereomers was achieved by HPLC using ion pair chromatography with nonanesulfonic acid sodium salt and LiChrospher 100 RP 18 as stationary phase. Quantification of O-demethyltramadol glucuronide and N,O-didemethyltramadol glucuronide in human urine was performed by fluorescence detection. The urine samples were purified by a two-step solid-phase extraction. The glucuronides were found to be highly enriched in the 1S,2S-diastereomers. The results of a study with three healthy volunteers are presented.