High-performance liquid chromatographic method for simultaneous determination of baicalein and baicalein 7-glucuronide in rat plasma

A simple HPLC method with ultraviolet detection was developed for the Simultaneous determination of baicalein and its major metabolite, baicalein 7-glucuronide (baicalin) in rat plasma. Following solid phase extraction with HLB cartridge, the analytes were separated using a gradient mobile phase consisting of methanol-acetonitrile-phosphate buffer. The flow-rate was set at 1 ml/min and the eluent was detected at 320 nm. The method is linear over the studied range of 1-10 and 0.05-1 mug/ml for baicalein and baicalin, respectively. The intra-day and inter-day variations of the analysis were less than 6.38%, with relative error ranging from -3.6 to 6%. The limit of quantification in plasma was 0.05 mug/ml for both baicalein and baicalin. The developed method proves to be an improved and more reliable method because of its capability for determining baicalein and baicalin simultaneously in a single chromatographic run. (C) 2004 Elsevier B.V. All rights reserved.