Narrowbore high performance liquid chromatography of berberine and palmatine in crude drugs and pharmaceuticals with ion-pair extraction using cobalt thiocyanate reagent.

For the simultaneous determination of berberine and palmatine from Phellodendri Cortex, Coptidis Rhizoma and pharmaceuticals, a new narrowbore HPLC method was developed with a simple and selective sample clean-up using cobalt thiocyanate reagent. Samples were sonicated with 2% hydrochloric acid for 30 min and protoberberine-type alkaloids in the resulting mixture were extracted with cobalt thiocyanate reagent and dichloroethane. The aliquot of dichloroethane layer was evaporated and the residue was dissolved for HPLC analysis. The recoveries of berberine and palmatine from Phellodendri Cortex, and Coptidis Rhizoma were better than 90%. Calibration curves for berberine and palmatine were linear over the concentration range of 0.1-50 microg/ml. Limits of quantitation for berberine and palmatine were 0.5 ng. This sample preparation process can be used for the identification of protoberberine-type alkaloids from crude drugs and oriental pharmaceutical preparations.