Rapid assay for theophylline in clinical samples by reversed-phase high-performance liquid chromatography.

A fast, sensitive and highly specific method for the determination of theophylline in human serum is reported. Using a C18-bonded reversed-phase column with an acetonitrile-acetate buffer mobile phase theophylline is completely resolved not only from other dietary xanthines and their metabolites but also from co-administered drugs such as paracetamol and phenobarbitone. Use of beta-hydroxyethyltheophylline as internal standard allows a within batch precision of 2.0% and a between batch variation of 3.0%. Factors involved in the development of the method and its performance are discussed.