SENSITIVITY OF PHENOLIC COMPOUNDS EVALUATED BY A NEW APPROACH OF ANALYTICAL METHODS

Phenolic compounds are a group of antioxidants with the capacity of combat free radical. These compounds present different behavior when evaluated by different methods. Thus, the objective of this study was to evaluate the behavior of phenolic compounds (gallic acid (GA), vanillic acid (VA), syringic acid (SA) and 4-hydroxybenzoic (HA) acid) in relation to the different methods (DPPH., ABTS.+, FRAP, TPC and ORAC) through the sensitivity for each compound. The DPPH. was performed according to Brand-Williams. The ABTS.+ according to Rufino. The FRAP according to Benzie and Strain and ORAC following the method of used the solution fluorescein. Five different concentrations (25, 50, 100, 150 and 200 µmol L-1) of phenolic compounds earlier cited were studied by all assays. The studies were realized in four replicates. . Results were statistically evaluated using PCA and Tukey’s test methodologies. The compounds sensitivity was obtained from the slope of the standard curves analytical . Limits of detection and quantification were calculated through the ratio among uncertainty of the linear coefficient (Sa) and angular coefficient (b). The ORAC methodology showed the major value for the slope parameter compared to other methods.. The sensitivity measure was higher for VA, followed by SA, GA, and HA . According to results, it is possible to conclude that the same phenolic compound shows different behavior when evaluated by different methodologies. Moreover, same class phenolic compounds respond differently once the same methodology is applied. It has been better confirmed with the PCA results. These results can be applying in real samples, indicating which methodology will be better adequate to provide reliable results, depending on the antioxidant composition of food.