The monitoring of ascorbic acid (AA), an essential dietary vitamin (Vitamin C) in the human body and its oxidative behavior has been studied in this work through a polymer based electrochemical sensor. The choice of polyindole (PIN), a conducting polymer, with the carbonaceous network or reduced graphene oxide (rGO) and silver nanoparticles (Ag) embedded in the matrix is shown to be an effective sensing material for the detection of ascorbic acid in a sample. The synthesized polymer nanocomposite (PIN/rGO/Ag) was characterized by structural, morphological and spectroscopic methods. The electro-oxidation of ascorbic acid to 3-dehydro ascorbic acid (DHA) was studied through cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV). The conditions of scan rate, pH and modifier concentration were optimized prior to sensing experiments. Using these optimal conditions, the ternary nanocomposite (PIN/rGO/Ag) exhibited excellent electrocatalytic activity towards ascorbic acid in the linear range of 0.2–1 mM, with a sensitivity 2.93 μA/mM-cm2. The limit of detection (LOD) for ascorbic acid was calculated to be 1.5 μM, while an LOQ value of 5.2 μM was obtained. The presence of common interferents such as urea, glucose and dopamine did not affect the current response of the sensor towards the analyte of choice. The designed electrochemical sensor was found to be highly selective towards ascorbic acid, stable and giving reproducible results over many potential cycles.
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