Abstract

A spectrophotometric method has been developed for the quantitative determination of antioxidant capacity. The assay is based on the reduction of Mo(VI)to Mo(V) by the sample analyte and the subsequent formation of a green phosphate/Mo(V) complex atacidic pH. The method has been optimized and characterized with respect to linearity interval, repetitivity and reproducibility, and molar absorption coefficients for the quantitation of several antioxidants, including vitamin E. The phosphomolybdenum method, in combination with hexane monophasic extraction, has also been adapted for the specific determination of vitamin E in seeds. The results obtained with the proposed method were validated by comparison with a standard HPLC method. The phosphomolybdenum method is routinely applied in our laboratory to evaluate the total antioxidant capacity of plant extracts and to determine vitamin E in a variety of grains and seeds, including corn and soybean. There is an increasing interest in the use and measurement of antioxidants in food, pharmaceutical, and cosmetic industries. This interest is rooted in the cumulative evidence that connects oxidative stress with numerous d egenerative d isorders ranging f rom p remature aging, pr ostaglandin-mediated i nflammatory processes, cancer, and a long series of diseases in which free r adicals ar e implicated (1, 2). In addition, many states implement very rigorous regulations on the use of food preservatives, so that they only allow