Application of Derivative Spectroscopy to the Determination of Plasma Theophylline in the Presence of Phenobarbital

Abstract
A rapid, simple, and sensitive procedure for the determination of theophylline in plasma using second derivative spectroscopy is described. Second derivative spectra of plasma extracts containing theophylline in concentrations ranging from 2 to 20 µg/mL were studied. The method is suitable for the measurement of plasma theophylline in patients treated for cardiorespiratory disorders. Interference from other compounds such as phenobarbital can be avoided.