a high performance liquid chromatography method was studied for determination of 18 ?-glycyrrhetinic acid in glycyrrhiza glabra l. (licorice) extract. the operating condition were c-18 reversed phase column (vp-ods, (250×4.6 mm, 5 mm)) at room temperature, acetonitril/phosphoric acid (3/1) as mobile phase, at flow rate of 0.6ml/min (0-8min), 0.4ml/min (8-20min) and uv detection at 230 nm. the r...