Voltammetric determination of vitamin D 3 with a rotating glassy carbon electrode

Abstract

A voltamperometric study (DC and DP) on the electroanalytical behaviour of vitamin D 3 in a methanolic solution using LiClO 4 as the supporting electrolyte and working with a glassy carbon electrode was carried out. Vitamin D 3 exhibits an oxidation wave (DC) or peak (DP) at potentials close to +1.1 V (versus SCE). The optimum experimental conditions for the best reproducibility of the voltamperometric signal were determined and the different parameters affecting the electrochemical process were studied. The electrochemical process was seen to be irreversible and, under certain conditions, adsorption of vitamin D 3 onto the electrode surface was observed. A voltamperometric procedure for the determination of vitamin D 3 in a concentration range of 2 × 10 −6−2 × 10 −4 M is proposed. The detection limit is of the order of 2 × 10 −6 M and the relative standard deviations are 1.1% (DC) and 2.6% (DP), respectively.