Amphetamine and methamphetamine determination in urine by reversed-phase high-performance liquid chromatography with simultaneous sample clean-up and derivatization with 1,2-naphthoquinone 4-sulphonate on solid-phase cartridges

A liquid-solid procedure is proposed for sample clean-up and derivatization of amphetamine and methamphetamine in urine samples. The reagent was 1,2-naphthoquinone 4-sulphonate, and a commercial C-18 packing cartridge was used. The samples derivatized at room temperature were chromatographed on a 5-mu m Hypersil ODS (250X4 mm I.D.) with an elution gradient of acetonitrile-water containing propylamine. Under these conditions, the amines were eluted with short retention times. The procedure was used to determine amphetamine, or methamphetamine with its metabolite amphetamine, in spiked urine samples. The detection limit (at a signal-to-noise ratio of 3) for amphetamine (0.1 mu g/ml) was similar to that obtained with liquid-liquid derivatization and to those obtained with immobilized reagents on a polymeric solid support. The detection limit for methamphetamine (0.4 mu g/ml) was higher than with the liquid-liquid procedure because of the lower reactivity on the cartridge. The precision and accuracy of the method were also studied.