Spectrophotometric determination of artemisinin and dihydroartemisinin

Abstract

A simple and rapid spectrophotometric method for the determination of artemisinin (ART) and dihydroartemisinin (DHA) is described. The method is based on the reaction of hydrogen peroxide (H₂O₂), generated by the cleavage of endoperoxide linkage of ART/DHA and its reaction with potassium iodide to liberate iodine. The liberated iodine bleaches the red coloured safranin O to colourless species and is measured at 521 nm. Beer’s law is obeyed in the range of 16-112 µg mL⁻¹ for both ART and DHA. The molar absorptivity, Sandell’s sensitivity, detection limit and quantitation limit for ART were found to be 0.3401x10⁴ Lmol⁻¹cm⁻¹, 1.43 x 10⁻² µg cm⁻², 0.0685 µg mL⁻¹ and 0.2075 µg mL⁻¹respectively; while that for DHA were found to be 0.2891 x 10⁴ L mol⁻¹cm⁻¹, 1.33 x10⁻² µg cm⁻², 0.0491 µg mL⁻¹ and 0.1488 µg mL⁻¹ respectively. The optimum reaction conditions and other analytical parameters were evaluated. The statistical evaluation of the method was examined by determining intra-day and inter-day precision.