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Ultraviolet—visible (UV—vis) spectrometry, electron paramagnetic resonance spectroscopy, high-performance liquid chromatography, and thin-layer chromatography were used for the evaluation of the antioxidant activity of natural samples. All the methods used free radicals to determine antioxidant capacity and standard antioxidant compounds, usually Trolox or vitamin C, to express the results. In this study, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) methods for the determination of the antioxidant activity of some wines previously separated by high-performance thin-layer chromatography (HPTLC) are statistically compared. The antioxidant activities were quantified based on the calibration curves obtained after elution under the same chromatographic conditions of different quantities of Trolox. Also, the reaction time was established to be between 10 and 30 min. The results show that the values found for DPPH and ABTS assays are well correlated, the values obtained in the case of ABTS being higher. The ABTS method is more sensitive than DPPH assay and is more useful than DPPH assay in the determination of the antioxidant activity of natural samples. In the case of real samples tested, the antioxidant activities decrease in the order red wines, rose wines, and white wines.
Danciu et al. (Wed,) studied this question.