2.8.3. Ferric reducing antioxidant power (FRAP)
Antioxidants are used as reductants in a redox-linked colorimetric method in
this assay (Celep et al., 2012). Ten microliters of properly diluted samples and
30 lL of Milli Q water were mixed with 260 lL of FRAP reagent in a microplate.
The mixture was incubated at 37 C for 30 min. After the incubation period, the
absorbance was read at 593 nm using a 96-well microplate reader. Water was used for the control group instead of sample. A standard curve was prepared using different concentrations of FeSO47H2O (0.25–2 mM). Butylated hydroxy toluene was used as the reference substance. The results were expressed as mM FeSO4 per gmaterial.