New antiradical capacity assay with the use potentiometric method.

For the first time, the dependence of a redox potential change during a reaction of peroxyl radical generation and their interaction with antioxidants was studied. A regular change of a potential is due to oxidation of an antioxidant by initiating peroxyl radicals accompanied by an electron transfer. An original direct method for determining induction periods, inhibition coefficients and an antiradical capacity using the potentiometric method is proposed. Using the proposed approach the induction periods and the inhibition coefficients of various OH, NH, SH containing antioxidants were determined. The antiradical capacity of a herbal extract was studied. A high degree of correlation with a DPPH assay was obtained. RSD results obtained using the proposed approach do not exceed 7%.