Electrochemical Behavior and Highly Sensitive Voltammetric Determination of Doxepin in Pharmaceutical Preparations...

In this manuscript, the electrocatalytic oxidation of doxepin (DOX) was studied at a carbon ionic liquid electrode, fabricated using graphite, and the ionic liquid 1-octylpyridinium hexaflourophosphate (OPFP). The surface of the proposed electrode was characterized by scanning electron microscopy. Differential pulse voltammetry was applied as an analytical technique for quantification of sub-micromolar concentration of doxepin. Various parameters were optimized for practical application. Under the optimal conditions, the proposed electrode exhibited interesting sensitivity toward determination of doxepin compared to the other conventional electrodes and the anodic peak current versus doxepin concentration was linear in the ranges of 0.05-24 µM. The detection limit of 21 nM was achieved. Cyclic voltammetry (CV) was also applied to acquire information about the reaction mechanism and calculating the kinetic parameters. The electroxidation process was irreversible and revealed adsorption controlled behavior. The method was successfully applied for determination of doxepin content in pharmaceuticals and blood serum samples.