title: Application of thermochromism in spectrophotometric analysis: selective determination of berberine in pharmaceuticals by solvent extraction.
abstract: A solvent extraction and spectrophotometric method for selective determination of berberine in pharmaceuticals is proposed. Berberine forms an ion associate with tetrabromophenolphthalein ethyl ester, which is extracted into ethylene dichloride. Secondary and tertiary amines and alkaloids are coextracted with the berberine and complicate the berberine determination. The absorbance of the secondary and tertiary amines and alkaloids into ethylene dichloride, however, decreases nearly to zero when the temperature is elevated from 25 to 60 degrees. Thus, berberine can be determined successfully in the presence of the secondary and tertiary amines and alkaloids by using thermochromaism.
mesh_terms: D001599:Berberine / Q000032:analysis*; D001600:Berberine Alkaloids / Q000032:analysis*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006358:Hot Temperature; D008722:Methods; D010635:Phenolphthaleins; D012997:Solvents; D013053:Spectrophotometry
chemical_list: D001600:Berberine Alkaloids; D010635:Phenolphthaleins; D012997:Solvents; D001599:Berberine