A new approach to assess the total antioxidant capacity using the TEAC assay

The trolox equivalent antioxidant capacity (TEAC) assay is a popular method for assessing the capacity of a compound to scavenge ABTS radicals (ABTS). Under the conditions in which the assay is performed, the reaction between most antioxidants and ABTS does not reach completion within the time span applied. This leads to an underestimation of the TEAC of these antioxidants. In the present study, incubations with different concentrations of ABTS and a fixed concentration of antioxidant were performed. The decrease in ABTS concentration in 6 min was plotted against the initial concentration of ABTS and fitted by an exponential function. Extrapolation of the fit to an infinite excess of ABTS gives the maximal concentration of ABTS that can be scavenged by the antioxidant at the concentration employed. This can be used to determine the actual TEAC of antioxidants, i.e. the total antioxidant capacity.