~1H NMR Method for Simultaneous Identification and Determination of Caffeine and Theophylline in Human Serum and Pharmaceutical Preparations

摘要

A ~1H NMR method for the simultaneous identification and determination of caffeine and theophylline in pharmaceutical preparations and human serum has been developed.~1H NMR spectrum of caffeine exhibits three sharp singlets at 2.75,2.93 and 3.40 ppm,while that of theophylline shows two singlet peaks at 2.77 and 2.97 ppm.For the purpose of quantitative ana-lyses of the mixtures of these two alkaloids 'H NMR spectra of caffeine and theophylline were compared to that of maleic acid as an internal standard at the constant temperature.The suitable peaks were selected and standard deviation and reproducibility of the results were studied applying the full factorial design method.The obtained detection limits are 1.6 mug mL~(-1) and 1.4 mug mL~(-1) for caffeine and theophylline,respectively.The average recove-ries of the studied compounds in various samples,pharmaceutical preparations and human serum ranged from 90.2 to 107.5%.