HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF THEOPHYLLINE AND ITS DERIVATIVES WITH ELECTROCHEMICAL DETECTION

Theophylline and its derivatives are determined by high-performance liquid chromatographic separation on a C8 reversed-phase column with electrochemical detection. The analyte is oxidized at 1.24 V (vs. the standard calomel electrode) on a wax-impregnated graphite electrode using classical DC and current sampled DC modes, and the results obtained compared with those of a 254 nm UV detector. Polarographic detection offers greater sensitivity for theophylline than UV detection; further, interferences which hamper UV detection may be selectively eliminated with polarographic detection. Theophylline (1,3-dimethylxanthine) is used in drug therapy for the control of asthma.