Generation of the ABTS [2,29-azinobis-(3-ethylbenzothiazoline-6-sulfonic
acid)] radical cation [18]
forms the basis of one of the spectrophotometric methods
that have been applied to the measurement of the
total antioxidant activity of solutions of pure substances
[12,19,20], aqueous mixtures and beverages
[7,8]. The original ABTS•1 assay was based on the
activation of metmyoglobin with hydrogen peroxide in
the presence of ABTS to produce the radical cation, in
the presence or absence of antioxidants. This has been
criticized on the basis that the faster reacting antioxidants
might also contribute to the reduction of the
ferryl myoglobin radical. A more appropriate format
for the assay is a decolorization technique in that the
radical is generated directly in a stable form prior to
reaction with putative antioxidants.