Analytical Studies on the Active Constituents in Crude Drugs. I. Determination of Berberine in Coptidis Rhizoma with Tetrabromophenolphthalein Ethyl Ester using Thin-Layer Chromatography

Abstract

Berberine in Coptidis Rhizoma and Oriental pharmaceutical preparations was determined with a small SD and a small coefficient of variation. The sample solution was separated by 2-dimensional TLC on a plate (20 .times. 20 cm) with 2 different developing solvents, n-BuOH:AcOH:H2O = 7:1:2 and cyclohexane:diethylamine = 9:1. The berberine portion was scraped off the plate and extracted with 1% HCL .cntdot. methanol. The extract solution was placed in a test tube. After evaporation of the solvent, 5 ml of phosphate buffer (pH 8.0) and 2 ml of phosphate tetrabromophenolphthalein ethyl ester (TBPE) solution (4.0 .times. 10-4 M) were added to the residue, and the solution was shaken with 5 ml of 1,2-dichloroethane. Berberine was extracted into the organic layer as a 1:1 ion-pair complex with TBPE. The color of organic layer was yellowish green (.lambda.max 610 nm). The quantitative determination of berberine in the range of 4.3-21.6 .mu.g is possible by the measurement of this color at 610 nm.