[Simultaneous determination of theophylline and its metabolites by HPLC]

A high performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of theophylline and its metabolites, with caffeine and its metabolites. The method is simple and applicable to planning the administration of theophylline. We used a column-switching system in combination with atmospheric pressure chemical ionization liquid chromatography-mass spectrometry (LC-APCI-MS) for the determination of theophylline and its metabolites in biological samples. In the mass spectrum, the molecular ions of these drugs and metabolites were clearly observed as base peaks. The method is sufficiently sensitive and accurate for the pharmacokinetic studies of these drugs.