Determination of thiopental by high pressure liquid chromatography

A specific and rapid reverse phase HPLC-method for the determination of thiopental in serum and in protein free solutions is described. No extraction is used. The detection limit is about 0.090 microgram/ml for serum and about 0.030 microgram/ml for buffer solutions. The retention time is 3.80 min. No interference is found with drugs commonly used in patients with heart diseases. The method was used to follow the serum concentrations in 7 patients who were given thiopental as an introduction to general anaesthesia.