Abstract

Total alkaloids (calculated as reserpine) from various samples of Rauwolfia serpentina root powder and its marketed formulation were estimated by spectrophotometric method using ion-pair complexation of acid dye (methyl orange) with the alkaloids. The complex was selectively extracted in to chloroform and by treatment with hydrochloric acid, the dye was liberated from the complex. The pink colour of the liberated dye is proportional to the amount of alkaloids which was measured at 530nm. The method adopted for extraction of alkaloids from samples has the advantage of extraction of mainly the alkaloids and not the other interfering substances. All the alkaloids extracted in this method were found to form complexes with the dye under the experimental conditions. Beer's law was obeyed between 5-40 μg/ml. The method was found to be simple, sensitive and accurate. It could be applied to formulations containing Rauwolfia and found suitable for routine quality control purposes.