Assays of antioxidant capacity: Optics and voltammetry

Low-molecular-weight antioxidants are chemical compounds that protect against oxidative damage. They play a substantial role in an organism, can be used as food or material preservatives, and can be used as substances applicable in pharmacology. Chemical identification of antioxidants is possible, but elaborative and expensive, because a high number of various antioxidant substances should be assayed. The antioxidant capacity as the sum of antioxidants in the tested sample is frequently performed. Optical assays such as the ferric reducing antiox-idant power assay (FRAP), the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, and the 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) assay are common. Voltammetry is an alternative to optical assays, providing some advantages over common optical methods. Basic optical and voltammetric assays for the determination of antioxidant capacity are described and discussed in this review.