[Development of the method for analysis of theophylline and its related compounds using capillary high-performance...

A convenient, reliable and sensitive method for analysis of theophylline (TH), theobromine (TB) and caffeine (CA) in biological samples by capillary high performance liquid chromatography (HPLC)/fast atom bombardment (FAB)-mass spectrometry (MS) was developed using 7-ethyltheophylline (7-ETH) as an internal standard (IS). The capillary column (0.3 mm i.d.) enabled the introduction of entire effluent to the frit interface for FAB-MS; and a special column switching device was utilized for sample concentration and gradient formation. These conditions realized simultaneous determination of the compounds of as low as 50-500 ng/ml concentrations. Actually, the compounds in blood and urine could be identified and quantified for healthy subjects having TH and/or CA spontaneously. In addition, TH in human hair obtained from the patients with bronchial asthma, who had taken 400 mg TH daily for more than 2 years, could be detected by the capillary HPLC/FAB-MS. This method seems very useful for the analysis of clinical or forensic samples, because of its ability of final drug identification.