2.5. Oxygen radical absorbance capacity (ORAC) analysis of distillation byproduct
After extraction with aqueous acetone in the ASE 350, the samples were brought up to 25 mL in the acetone–water–acetic acid solution. This solution was transferred into a scintillation vial, and later diluted for ORAC analysis. The ORAC assay is based upon the inhibition of the peroxyl-radical-induced oxidation initiated by thermal decomposition of azo-compounds such as [2,2′-azobis(2-amidino-propane) dihydrochloride (AAPH)] (Prior et al., 2003). Samples were analyzed for their artemisinin concentration and their antioxidant capacity (ORAC) in triplicates.