Original Articles: 2015 Vol: 7 Issue: 6
Quantitative titrimetric and spectrophotometricdetermination ofdihydroartemisininbased on the redox reactionwithcerium ammonium sulphate
Two titrimetric and one sensitive spectrophotometric methods are developed for the determination of Dihydroartemisinin (DHA) in bulk and in tablets formulations. Titrimetric method A is based on the generation of hydrogen peroxide from DHA in acid medium in situ; which is titrated against cerium ammonium sulphhate to a ferroin sky blue end point. The second titrimetric method B is based on the initial oxidation of the drug DHA with known excess of cerium ammonium sulphate and then back titrating the excess oxidant with ferrous ammonium sulphate using ferroin as an indicator. In the third method the drug was oxidized by cerium ammonium sulphate the oxidant in acid medium with the addition of ferroin indicator resulting in a sky blue chromogen measured spectrophotometrically at 510nm. The amount of cerium ammonium sulphate used was proportional to the drug concentration in all three methods proposed. The applicable range for both titrimetric method A and B were 2- 20mg/ml and 1-15mg/ml respectively. The calibration graph generated in the spectrophotometric method was linear obeying Beer’s law in the range of 1.0 - 10μg/ml. The method were validated for accuracy, precision, selectivity and successfully applied in the determination DHA tablets brands procured locally with no interference from pharmaceutical excipient. Statistically the proposed methods showed good congruence with official pharmacopoeial method.