Voltammetric determination of cholecalciferol at glassy carbon electrode performed in water ethanol mixture

• Main Authors: Arlinda Nallbani, Julie Holubová, Milan Sýs, Tahir Arbneshi, Karel Vytřas
• Format: Article
• Language: English
• Published: HACCP Consulting 2018-03-01
• Series: Potravinarstvo
• Subjects: cholecalciferol; anodic differential pulse voltammetry; glassy carbon electrode; vitamin food supplements
• Online Access: http://www.potravinarstvo.com/journal1/index.php/potravinarstvo/article/view/889

<p>To confirm or disprove previous hypotheses, cyclic voltammetry of 0.5&nbsp;mM cholecalciferol (vitamin&nbsp;D₃) at glassy carbon electrode (GCE) and platinum disk electrode (PtE) in pure acetonitrile and water‑ethanol mixture at 50&nbsp;mV&middot;s^‑1 has been used to investigate the oxidation mechanism. The oxidation occurs in two one-electrone steps. According to calculation of the highest electron density in cholecalciferol molecule which is evidently delocalized over carbon atoms of the three conjugated double bonds (C19, C10, C5-C8) points to part of the molecule involved in oxidation processes. An oxidation peak (at +0.925 V vs. Ag/AgCl) was used to develop direct voltammetric method based on differential pulse voltammetry for the vitamin&nbsp;D₃ determination at GCE performed in 40% ethanol containing 0.1&nbsp;M LiClO₄. Under optimization of analytical procedure, it was found that a composition of the supporting electrolyte used significantly affects a current response of oxidation peak obtained. Satisfactory sensitivity was achieved in the 1:1 water‑ethanol mixture containing 0.05&nbsp;M lithium perchlorate as as supporting electrolyte. The linear range for vitamin&nbsp;D₃ determination was <br /> 2.4&nbsp;&times;&nbsp;10^-6&nbsp;-&nbsp;3.5&nbsp;&times;&nbsp;10^-4&nbsp;M with the detection limit of 8.0&nbsp;&times;&nbsp;10^-7&nbsp;M. This work demonstrates a fact that the GCE is suitable electroanalytical device for analysis of various food supplements and medicaments.</p> <br />