The Sodium Hypochlorite Method for the Photometric Determination of Berberine

In this paper, the visible absorption spectra of a red colour, produced by adding one drop of the solution of sodium hypochlorite (containing about 2.6 to 2.8 mg chlorine per 100 ml) to a solution of berberine hydrochloride in 8 N hydrochloric acid, were studied. The red colour is stable within 2 hours and a procedure is proposed as follows: Accurately pipette 0, 1, 2, 3, 4, 5 ml of the standard solution (equivalent to 0, 0.1, 0.2, 0.3, 0.4, 0.5 mg of anhydrous berberine hydrochloride) into 25 ml volumetric flasks respectively, add water to make 5 ml. Dilute the solution to about 20 ml with 10 N hydrochloric acid, mix well, allow to stand for 10 minutes, and determine the optical density at 510 mμ (first solution as blank). Accurately pipette 5 ml of sample solution (equivalent to 0.25 mg of berberine hydrochloride) into 25 ml volumetric flask and proceed as above. The colour intensity was found to obey Beer's law within the range of 0.1 to 0.5 mg of anhydrous berberine hydrochloride per 25 ml. The percentage of error of this method is -1.54 to +1.50%. The results of determinations of berberine hydrochloride tablet, berberine hydrochloride injection, and berberine citrate injection are in agreement with those obtained by the official method. This method may be applied to the determination of berberine in the presence of hydrastine with no interference.