HIGHLY SENSITIVE AND RAPID-DETERMINATION OF THEOPHYLLINE, THEOBROMINEAND CAFFEINE IN HUMAN PLASMA AND URINE BY GRADIENT CAPILLARY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY FRIT-FAST ATOM BOMBARDMENT MASS-SPECTROMETRY

A sensitive and reliable analytical procedure has been established for the detection of theophylline (TH), theobromine (TB) and caffeine (CA ) in human plasma and urine by gradient capillary high-performance liq uid chromatography (HPLC)-frit-fast atom bombardment mass spectrometry (FAB-MS) (LC-frit-FAB-MS), Two capillary columns and a column-switchi ng valve were used in this LC system to allow all of the sample inject ed to be introduced into the MS system. 7-Ethyltheophylline was used a s the internal standard (I.S.). The xanthines in the specimen were ext racted with an Extrelut column. The lowest detected amount was ca. 5 n g/ml using this method.