Determination of carbimide in plasma by gas-liquid chromatography

A sensitive and selective method for the measurement of carbimide, the hydrolytic product of calcium carbimide, in plasma is described. The procedure involves extraction with ethyl acetate, derivatization with heptafluorobutyric anhydride and analysis by gas-liquid chromatography with electron-capture detection. The lower limit of sensitivity of the assay is 5.0 ng/ml carbimide in plasma. The overall accuracy of the procedure is 96.1% with a coefficient of variation not exceeding 8.7%. This assay has been used to investigate the time-course of plasma carbimide concentration in the rat following oral administration of calcium carbimide.