Assay of Dihydroartemisinin by Iodometric Titration
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Abstract
The iodometric titration method is developed for the determination of dihydroartemisinin in
tablets and in bulk powders. The method is based on the redox reaction between the drug and
potassium iodide in acid condition. Iodine is generated in situ by this reaction. The liberated iodine
is then titrated with standardised sodium thiosulphate reagent with boiled starch as indicator. It
was found that the percentage content of active ingredient per tablet was 98% which falls within
the International pharmacopoeia standard (90-110%). This titrimetric method is based on a 1:1
reaction stoichiometry of dihydroartemisinin: iodine. This method is applicable over the range of 5-
70mg and was used to assay other popular brands of dihydroartemisinin like Alaxin, Cotecxin and
Santexin tablets sold in drug outlets in Uyo, Nigeria. The proposed method was found to be very
useful when applied to these tablet preparations with mean recoveries of 98% to 104%.The method
was evaluated for precision, accuracy and recovery studies using standard addition technique,with
the relative error of < 2%, RSD < 3% and a coefficient of variation < 3%. The results of this method
was statistically compared with the reference method by applying the students t-test and F-test at
95% confidence level ( t = 2.77 and F = 6.33) the calculated t and F values did not exceed the
tabulated values at 4 degrees of freedom showing no significant difference between the proposed
method and the reference method in terms of precision and accuracy.
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