Voltammetric determination of vitamin B₆ (pyridoxine) at a graphite screen-printed electrode modified with graphene oxide/Fe₃O₄@SiO₂ nanocomposite

The preparation and study of electrochemical properties of a graphite screen-printed electrode (SPE) modified with the GO/Fe₃O₄@SiO₂ (GO is graphene oxide) nanocomposites are described. The morphologies of the GO/Fe₃O₄@SiO₂ nanocomposites were examined by scanning electron microscopy. The electrochemical oxidation of vitamin B₆ (pyridoxine) on SPE modified with the GO/Fe₃O₄@SiO₂ nanocomposite was investigated by cyclic voltammetry, differential pulse voltammetry, and chronoamperometry. Under optimum conditions (pH 7.0), the vitamin B₆ oxidation at the surface of the modified SPE occurs at a potential about 190 mV less positive than that at the unmodified SPE. A linear voltammetric response for vitamin B₆ was obtained in the concentration range 1.0•10 ⁶—9.0•10 ⁴ mol L^–1 with a detection limit of 5.2•10 ⁷ mol L^–1 using differential pulse voltammetry. The developed sensor was also successfully applied for determination of trace level of vitamin B₆ in both the standard vitamin B₆ sample and biological samples (urine).