Determination of Ascorbic Acid by Electrocatalytic Voltammetry with Methylene Blue.

A rapid voltammetric method was developed for the determination of L-ascorbate using methylene blue as a mediator with a glassy carbon electrode. The magnitude of the peak current that occurs near -0.04 V vs. Ag/AgCl is proportional to L-ascorbate concentration in the range of 1.2 × 10[SUP-6) to 1.12 × 10[SUP-3] M. The limit of detection is 1 × 10[SUP-6] M. Eight replicate analyses of 5.0 × 10[SUP-5] M and 4.5 ×10[SUP4] L-ascorbate yielded RSD values of 1.9 and 1.6%, respectively. The method was applied to the determination of ascorbic acid in fruit juices and vitamin C tablets. [ABSTRACT FROM AUTHOR]