Voltammetric determination of vitamin D3 with a rotating glassy carbon electrode

Voltammetric Studies on Vitamins D2 and D3 in Organic Solvents

“…It is likely that oxidized species were adsorbed on the electrode surface, thereby partially blocking the surface and lowering the surface area available for oxidation and leading to a corresponding decrease in current. Previous electrochemical studies have reported similar adsorption phenomena at glassy carbon electrodes during the oxidative scans of vitamin D [13][14][15]. According to the Randles-Sevcik equation [26], the peak current (I p ) is proportional to the square root of the scan rate ( ) for a diffusion controlled electrochemically reversible process,…”

“…Liu et al [14] performed CV experiments on vitamin D 2 in ethanol and detected an oxidative peak (E p ox ) at approximately +1.2 vs. Ag/AgCl/V on the forward scan. Mendez et al [15] observed an oxidative wave at +1.1 vs. SCE/V (saturated calomel electrode) during differential pulse voltammetry of vitamin D 3 in methanol. It was concluded that vitamin D compounds undergo chemically irreversible voltammetric oxidation processes at glassy carbon electrode surfaces [15] because no reduction peaks were observed when the scan direction was reversed [13,14].…”

“…Mendez et al [15] observed an oxidative wave at +1.1 vs. SCE/V (saturated calomel electrode) during differential pulse voltammetry of vitamin D 3 in methanol. It was concluded that vitamin D compounds undergo chemically irreversible voltammetric oxidation processes at glassy carbon electrode surfaces [15] because no reduction peaks were observed when the scan direction was reversed [13,14]. A common problem reported across these electrochemical studies was a decrease in the oxidative peak currents (I p ox ) when the potential range was cycled repeatedly due to weak adsorption at the electrode surface of the products of the oxidation.…”

Electrochemical Determination of Vitamin D3 in Pharmaceutical Products by Using Boron Doped Diamond Electrode

“…Moreover, electrochemical determination has the potential to be simply miniaturized, and analysis can be done in situ, without the need of sample transport to laboratory, with immediately accessible results. So far a limited number of the electrochemical methods dealing with direct vitamin D 3 electroanalysis have been published using bare [20][21][22] or modified [23][24][25] glassy carbon electrode (GCE), and platinum electrode [21] as the working electrodes.…”

Unmodified glassy carbon electrode as a reliable sensor for sensitive voltammetric quantification of vitamin D3

“…In the light of these demands, voltammetric methods can meet these rigorous requirements, and can serve as an alternative method for cholecalciferol determination. Despite numerous advantages provided by voltammetric techniques, so far a small number of papers enabling the quantification of vitamin D 3 in real samples have been published (7)(8)(9)(10)(11)(12)(13). The use of glassy carbon electrode (GCE) as a working electrode for quantification purposes of this vitamin has already been apperceived in the literature (9,13).…”