METHOD FOR THE DETERMINATION OF 5,5-DIPHENYLBARBITURIC ACID AND ITS SEPARATION FROM 1,3-DIMETHOXYMETHYL-5,5-DIPHENYLBARBITURIC ACID IN PLASMA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A method is described for the measurement of 5,5-diphenylbarbituric ac id in plasma using high-performance liquid chromatography with UV dete ction. Briefly, the compounds are separated on a C-18 reversed-phase c olumn using a mobile phase of 50 mM sodium acetate (pH 4.5) and methan ol. The flow-rate is 1.0 ml/min and 25 mu l are injected and detected at 215 nm. The method is specific and sensitive in the range of concen trations tested, with a limit of quantification of 0.25 mu g/ml. The c alibration curves are linear for concentrations between 0.25 and 10 mu g/ml. Intra-day and inter-day coefficients of variation are less than 8.5 and 10.5%, respectively, over the linear range. Intra-day and int er-day bias are less than 7.0 and 8.0%, respectively. A pharmacokineti c study conducted in male Beagle dogs administered 10 mg/kg of 1,3-dim ethoxy methyl-5,5-diphenylbarbituric acid or 8 mg/kg of 5,5-diphenylba rbituric acid intravenously demonstrates the utility of this method. ( C) 1998 Elsevier Science B.V. All rights reserved.