Square wave voltammetric determination of ascorbic acid in food and pharmaceutical samples using a novel room temperature ionic liquid ZnO nanoparticles carbon paste electrode



In this paper we report synthesis and application of ZnO nanoparticle (ZnO/NPs) and 1, 3-dipropylimidazolium bromide as high sensitive sensors for voltammetric determination of ascorbic acid (AA) using carbon paste electrode. The ZnO/NPs was characterized with different methods such as TEM and XRD. The cyclic voltammogram showed an irreversible oxidation peak at 0.35 V (vs. Ag/AgClsat), which corresponded to the oxidation of AA. Compared to common carbon paste electrode, the electrochemical response was greatly improved. The electro-oxidation of AA occurred in a pH-dependent 2e− and 2H+ process, and the electrode reaction followed a diffusion-controlled pathway. Under the optimum conditions, the voltammetric oxidation peak current of AA showed two linear dynamic ranges with a detection limit of 0.04 μM for AA. The novel sensor has been found selective and successfully implemented for the determination of AA in fresh vegetable juice fruit juices, tablet and tablet samples without previous preparation and were compared with a published electrochemical method.