Detection of vitamin C in various falsified oral formulations using voltammetry

Healthcare supplements are prime targets to be made into falsified products as they undergo less stringent regulation and can be purchased through online sites. There is an upsurge in the purchase of vitamin C due to the COVID19 pandemic which has made this product a target for falsification. Vitamin C can be available in various oral formulations and thus sample preparation is required prior to analysis. Chromatography and spectroscopy are the most widely used approaches for analysis. Therefore, this study focused on investigating if voltammetry could provide a rapid measurement approach of various formulations (normal, chewable, and effervescent tablets) of vitamin C without the need for any sample analysis. We found that tablet excipients reduce the oxidation peak current and influence the peak shape and oxidation peak potentials. This variation in the oxidation peak potential provided the ability to distinguish between the different oral formulations. Voltammetry provided the ability to conduct repeatable measurements and the solutions of the tablets were stable for 2 days for measurements. In a blinded study, voltammetry was able to identify the concentration of vitamin C present and the type of oral formulation of various falsified samples. Our findings highlight that voltammetry can be a vital technique for the determination of falsified healthcare supplements.