Abstract
A simple and sensitive reduced graphene oxide-modified glassy carbon electrode-based electrochemical sensor was used for the concomitant determination of gallic acid (GA) and protocatechuic (PA) acid. The prepared sensor showed a significant enhancement in synergetic electro-catalytic performance towards GA and PA oxidation. A good resolution of the voltammetry peaks was obtained and a method of square wave voltammetry was developed for detection. The modified electrode was characterized by electrochemical techniques. The optimal experimental parameters were considered. GA and PA exhibited a linear increase in the peak currents with their concentrations in the range from 20 to 144 µmol·L−1 for GA and from 20 to 166 µmol·L−1 for PA, with limits of detection (S/N = 3) of 30.8 µmol·L−1 for GA and 10.2 µmol·L−1 for PA. The sensor applicability was simultaneously tested for the analytical determination of GA and PA in mango juice and exhibited a robust functionality.
Highlights
Gallic acid (GA, 3,4,5-trihydroxybenzoic acid) and protocatechuic acid (PA, 3,4-dihydroxybenzoic acid), the most representative phenolic acids in fruits and vegetables, are strong antioxidants
On progressing the the decrease of current continues until a stable baseline current is reached. This indicates that the cyclic voltammetry (CV) scans, the decrease of current continues until a stable baseline current is reached
The active surface area was calculated to be 0.051 and 0.073 cm2 for the bare and modified electrodes, respectively. These results indicate that the active surface area of the modified GC electrode is increased by the presence of graphene (×1.45 more)
Summary
Gallic acid (GA, 3,4,5-trihydroxybenzoic acid) and protocatechuic acid (PA, 3,4-dihydroxybenzoic acid), the most representative phenolic acids in fruits and vegetables, are strong antioxidants They are present in a wide variety of fruits such as bananas, citrus fruits and mangoes as well as in green tea and several other plants. Voltammetric responses can overlap and this makes their simultaneous determination highly difficult To overcome this problem, modification of the glassy carbon electrode (GCE) was developed using reduced graphene oxide (rGO). This is due to their unique properties, such as wide potential windows, inertness as a catalyst and good electro-catalytic activity. Reduced graphene oxide composite is widely used as a building block of electrochemical sensors for the simultaneous determination of phenolic compounds. The applicability of the sensor was tested for simultaneous quantification of gallic acid and protocatechuic acid in a real mango juice sample
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