title: Evaluation of a glassy-carbon electrode for amperometric detection of selected methylxanthines in serum after their separation by reversed-phase chromatography.
abstract: We examined the relative merits of direct-current, pulse, and differential pulse amperometry at a flow-through, glassy-carbon electrode used in monitoring column chromatography. We give a rapid, simple procedure for determining theophylline (1,3-dimethylxanthine) in 20--100 microliter of blood serum. Interference by 1,7-dimethylxanthine, a metabolite of caffeine, is compared for photometric and amperometric detection, and some advantages of combined photometric and amperometric detection are discussed.
mesh_terms: D002853:Chromatography, Liquid; D004563:Electrochemistry; D004566:Electrodes; D006801:Humans; D008722:Methods; D013806:Theophylline / Q000097:blood; D014970:Xanthines / Q000097:blood* / Q000302:isolation & purification
chemical_list: D014970:Xanthines; D013806:Theophylline