Electrochemical Evaluation of the Catalytic Effect of Natural Phosphate on the Oxidation of Aascorbic Acid: Analytical Application in Human Blood

This work describes the electroanalytical activity of the natural phosphate modified carbon paste electrode (CPE-NP) for ascorbic acid (AA) oxidation, where its electrochemical response is compared to the carbon paste electrode (CPE). The voltammetric behavior of AA was studied when an anodic peak has appeared at 0.35 V (vs. Ag/AgCl/3 M KCl) in the Britton Robinson buffer solution (pH 6.0). This peak was obtained from the irreversible oxidation of AA at CPE-NP. The electro-catalytic influence was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). To give electroanalytical detection to oxidizing the AA on the CPE-NP, the differential pulse voltammograms have been used in the potential range from -0.5 V to 1.5 V vs. Ag/AgCl/(sat. KCl). Besides, CPE-NP can be employed successfully to ameliorate the detection of AA at very feeble concentration with good sensitivity. The calibration range has been from 1.0 × 10-6 to 1.0 ×10-3 mol L-1. The calculated limit of detection (LD) is 1.44 × 10-9 mol L-1 when the relative standard deviation (RSD) at 1.0× 10-5 mol L1 AA concentration was 3.29% for nine repetitions. Afterward, the studied method has been applied to detect AA in human blood with satisfactory results.