Comparison of the Simple Cyclic Voltammetry (CV) and DPPH Assays for the Determination of Antioxidant Capacity of Active Principles

Abstract

Antioxidant activity of a number of small (low molecular weight) natural compounds found in spices, condiments or drugs (gallic acid, sesamol, eugenol, thymol, carvacrol, vanillin, salicylaldehyde, limonene, geraniol, 4-hexylresorcinol, etc.) has been evaluated using electrochemical and DPPH• radical scavenging measurements. Structural analysis of the tested compound suggest a remarkable activity for phenol derivatives and the importance of the -R groups located on the phenolic ring in the molecule's ability to act as free radical scavenging as well as their influence in the electrochemical behavior. The voltammetric method can be used for the determination of the antioxidant capability in the same manner as the DPPH • radical scavenging because of the correlation found between oxidation potentials and anti-radical power (ARP = 1/EC 50 ). Such electrochemical determination is fast and cheap and allows making measurements under a variety of experimental conditions. The accuracy of the electrochemical measurements is the same for all the compounds, irrespective of their scavenging activity, the opposite of what occurs in the DPPH • test.

Electrochemical Methods for Total Antioxidant Capacity and its Main Contributors Determination: A review

“…The measured signal is independent on the distance that radiation travels in the analytical cell or on the turbidity, and the dynamic range is quite extended [36][37][38][39][40]. One aspect in favour of the electrochemical methods is the electroactivity of most antioxidants, the electron transfer being involved in antioxidant -free radical reactions, enabling a prompt screening of the antioxidant capacity of a series of organic biocompounds even in complex or coloured samples [37][38][39][40][41].…”

“…The parameter most oftenly referred to is the oxidation potential at the glassy carbon electrode, but its value was found to be strongly dependent on the reaction mechanism at the electrode's surface [41].…”

“…Voltammetry as potentiodynamic assay is based on the recording of the current intensity at controlled potential variation and exploits the reducing ability of antioxidants or the reversibility of redox active substances which are either single or part of a sample [36][37][38][39][40][41]. The confirmed analytical advantages of the various voltammetric techniques are: enhanced sensitivity, a broad concentration range (10 -12 to 10 -1 M), numerous appliable solvents and electrolytes, wide working temperature ranges, fast analysis, simultaneous determination of analytes (organic and inorganic), the capacity to assess kinetic and mechanistic parameters (including reasonable estimation of unknown ones), the facility of different potential waveforms generation yielding low current intensity values, these features being sustained by a strongly developed theoretical backround [42].…”

Electrochemical Pseudo‐Titration of Water‐Soluble Antioxidants

“…Electrochemical-based sensors have been used for measuring the AO activity due to their simple, fast and reliable analytical performance on biological and food samples [29][30][31][32][33][34][35][36]. Moreover, electrochemical strategies can also take into account the complete range of chemical and biochemical interactions between all present species, including recycling or auto-oxidation processes.…”

Electrochemical Sensing of Ascorbic Acid on ZnO-decorated Reduced Graphene Oxide Electrode

“…Electrochemical determination of ascorbic acid is gaining interest due to its fast analysis, ability to detect lower concentrations, and simplicity of operation. Further, a lab-on-a-chip electrochemical sensing platform has the potential to simultaneously determine multiple antioxidants such as polyphenols as well as other micronutrients in a food sample [5,[10][11][12][13][14][15][16][17]. Therefore, the development of electrochemical sensing platforms that have the ability to determine multiple analytes relevant in nutritive food formulations and nutraceuticals is of paramount interest.…”