Determination of Theophylline in Plasma by High Performance Liquid Chromatography

Abstract

We describe a rapid and highly specific method for determining theophylline in plasma. Following addition of ammonium sulfate and β-Hydroxy-ethyl-theophylline as internal standard, theophylline is extracted into a mixture of chloroform hexane (70 : 30) and evaluated by high performance liquid chromatography, using Microporasil “Waters” 10 μm as stationnary phase and N-hexane-ethanol (76 : 24) mixture as mobile phase. Absorption at 280 nm is monitored. The method has a good precision (coefficients of variation between 3% and 4% for 1 mg/1 and 10 mg/1) and its sensitivity is about 0.25 mg/1. No interferences from endogenous compounds, metabolites of theophylline, or from drugs commonly co-administrated with theophylline have been encountered. This technique can be used in analytical toxicology, and also for therapeutic controls and pharmacokinetic studies.