Detection of Ascorbic Acid in Biological Samples by a New Modified Glassy Carbon Electrode

The present work describes the construction of a new modified electrode by casting the appropriate mixture of a metallocene, which has been introduced in the experimental part, as a mediator at the surface of glassy carbon (GC) electrode. The proposed modified GC electrode was used for the determination of ascorbic acid (AA) in phosphate buffer (PB) solution (pH = 4.0). When compared to bare GC electrode, the modified electrode not only shifted the oxidation potential of AA towards less positive potential but also enhanced its oxidation peak current. Further, the oxidation of AA was highly stable at modified electrode. The optimum analytical conditions were sought. The oxidation peak of AA increases linearly while increasing its concentration with a correlation coefficient of 0.9993 and a detection limit (3σ) was found to be quite desirable. The present modified electrode was also successfully used for the determination of AA in the presence of common interferences such as starch, glucose, citric acid Na+, K+, Mg2+ and Ca2+. The proposed modified electrode was successfully demonstrated towards the determination of AA in pharmaceutical samples. It should be noted that procedure for preparation of this modified electrode is simple, inexpensive and rapid.