Measurement of dextropropoxyphene and nordextropropoxyphene in biological fluids.

Detection, identification and measurement of dextropropoxyphene and its principal plasma metabolite, nordextropropoxyphene, can be important in the diagnosis of acute poisoning. A combination of thin-layer chromatography (TLC) and gas-liquid chromatography (GLC) of solvent or solid-phase extracts of urine or gastric contents usually serves to detect these and many other compounds, and an homogeneous enzyme immunoassay (EMIT-DAU) is also available for dextropropoxyphene. Measurement of dextropropoxyphene by GLC is complicated by the instability of this compound under certain conditions. However, a relatively polar stationary phase such as Carbowax 20M together with nitrogen-selective detection can give adequate sensitivity and selectivity for the measurement of the plasma concentrations attained after overdosage. High-performance liquid chromatography (HPLC) has not been widely applied in the assay of dextropropoxyphene and nordextropropoxyphene since these compounds have no pronounced ultraviolet absorption or fluorescence spectra. However, electrochemical oxidation detection can be used with a silica column/non-aqueous ionic eluent system. This gives good selectivity and sensitivity, and can facilitate the measurement of both compounds in plasma specimens after single oral dosage.