Simple method for determination of terbutaline plasma concentration by high-performance liquid chromatography

A method is described in which low nanomolar concentrations of terbutaline in plasma can be quantitated by use of a standard isocratic high-performance liquid chromatography system with electrochemical detection. Samples were prepared for injection by solid-phase extraction and preserved from degradation by addition of glutathione. Terbutaline and internal standard metaproterenol were resolved from plasma constituents on a single C₁₈ column by ion-pairing chromatography. The method is precise and accurate for measurement of freebase concentrations as low as 4.4 nmol/l (1 ng/ml).