Electrochemical Determination Of Ascorbic Acid Using A Carbon Paste Electrode Modified With Anthraquinone

Abstract

In this work, an electrochemical method for the determination of ascorbic acid using anthraquinone modified carbon paste electrode was developed. The electrode modification has been performed by mixing varying amounts modifier (anthraquinone), carbon paste and the solvent (paraffin oil) for homogenization. Under the optimized conditions. Anthraquinone modified electrode increased the peak currents of ascorbic acid, and greatly lowers the peak potential separation, compared to unmodified counterpart. Optimization of different variables such as pH of the working solution, scan rate, modifier composition and cyclic voltammetry parameters were made to improve the efficiency of the method. Moreover, the data reproducibility and electrode stability and recovery for the analysis were evaluated. The developed method was used for electroanalysis of ascorbic acid from pharmaceutical samples collected from Pharmacies at Jimma town. The peak potential shift with pH in the range 3.0 to 8.0, indicating participation of protons during the oxidation of ascorbic acid. Under optimized conditions and cyclic voltammetric parameters, an excellent linear dependence of the oxidative peak current on concentration of ascorbic acid was observed in the range 5×10-6 - 1×10-4 M with limits of detection (LOD) and quantification (LOQ) of 1.63 and 5.44 μM, respectively. Percentage recovery results being 98.5% for spiked standard ascorbic acid in pharmaceutical tablets. This method confirmed the potential applicability on the determination of ascorbic acid in real samples