Rapid determination of theophylline in serum by electron-capture GLC

A rapid and sensitive GLC procedure was developed for the determination of theophylline in serum. After extraction from serum with ethyl acetate, theophylline and the internal standard were derivatized with pentafluorobenzyl bromide under alkaline conditions. The derivatives were quantitated by electron-capture detection. The method has a sensitivity of 0.1 microgram/ml with a 0.1-ml serum sample.