Electrochemical properties of ascorbic acid and folic acid under acidic solution

Ascorbic acid and folic acid are very important vitamins which have some crucial roles in human body's metabolism, including enhancing iron absorption. Regardless of its roles, these vitamins are also known to be unstable and easily degraded in the processing by oxygen, pH, temperature, and UV light. Nowadays, microencapsulation may be a proper technique to overcome some of these shortcomings. However, there is a possibility of the changes in vitamin stability during encapsulation processes, particularly while using chitosan and acetic acid as wall material and solvent, respectively. In this study, cyclic voltammetry method was carried out for investigating the electrochemical properties of ascorbic acid and folic acid under acidic medium. The effect of scan rate (0.1; 0.2; 0.3 V/s) on the observed current was also studied. Furthermore, vitamin-aquadest solutions were also studied as a referred sample. Cyclic voltammetry was conducted using a three electrodes configuration connected to an electrochemical analyser. Platinum wire, graphite, and Ag/AgCl were employed as the working, auxiliary and reference electrodes, respectively. All the solutions were maintained for free oxygen by the degassing process. In general, the recorded currents of all solutions were increased while using a higher scan rate. Cyclic voltammogram also showed that ascorbic acid had two anodic peaks and two cathodic peaks which indicated that ascorbic acid undergoes reversible reaction. However, folic acid only had one anodic peak in water which represented an oxidation reaction. Furthermore, the electrochemical properties of ascorbic acid have a similar profile with folic acid while were in acidic solutions. Both vitamins have more positives anodic peak; hence depicted that acid could suspend the oxidation reaction.