Liquid chromatographic analysis of thiopental in blood and tissues

A liquid chromatographic method for the quantitation of thiopental in blood and tissues is presented. Quantitation in blood utilizes a single step dichloromethane extraction at pH 5.5. After mixing and centrifugation, the organic layer is evaporated to dryness at 40 degrees C and the residue reconstituted with methanol. Tissue extraction includes an alkaline clean-up step followed by re-extraction with dichloromethane after acidification. Either of two 10 mu columns can be used: a C8 or a C18 column. The mobile phase was methanol:water (60:40) at a flow of 2 mL/min. The wavelength of detection was 290 nm. Thiopental can be detected to 1 mg/L using this procedure, and no interferences with other acidic or neutral drugs were found.