Determination of Total Antioxidant Capacity of Lipophilic and Hydrophilic Antioxidants In the Same Solution by Using Ferric–Ferricyanide Assay

Abstract

The purpose of this work is to develop a simple, low-cost, and diversely applicable antioxidant capacity assay, the ferric–ferricyanide method based on Prussian blue formation, for both lipophilic and hydrophilic antioxidants in food matrices. The trolox equivalent antioxidant capacities of various antioxidant compounds were calculated with respect to the ferric–ferricyanide, FRAP, and modified CUPRAC methods. The linear calibration curves of the ferric–ferricyanide assay for lipophilic antioxidants (as absorbance vs. concentration) in 1:9 (v/v) H2O–acetone mixture solution with and without 2% MβCD were comparatively drawn. Simultaneous determination of lipophilic and hydrophilic antioxidants could be achieved without using MβCD. Testing of synthetic mixtures of lipophilic and hydrophilic antioxidants in 1:9 (v/v) H2O–acetone medium with the proposed method yielded the theoretically expected antioxidant capacities, considering the additivity of absorbances of constituents obeying Beer’s law. The proposed assay is simple, versatile, and cost-effective; its reagents are cheap and stable, and can be performed using a simple colorimeter.