Nanostructured Ni-Zeolite Y and Carbon Nanohorns Electrode for Sensitive Electrochemical Determination of B-Group Vitamins

This work presents the fabrication and analytical application of nanostructured Ni-zeolite (NiZY) and carbon nanohorns (CNHs) modified glassy carbon electrode (NiZY/CNHs-GCE) in the differential pulse voltammetric (DPV) determination of vitamin B₂ (VB₂) molecules. The synergistic combination of NiZY and CNHs significantly enhances the electrochemical performance of the sensor, as confirmed by structural, textural, morphological, and electrochemical studies. The redox behavior of VB₂ on NiZY/CNHs-GCE was found to be adsorption-controlled, involving a two-electron, two-proton reversible reduction process. Under optimized conditions, the DPV response of NiZY/CNHs-GCEs in McIlvaine buffer solution (pH 3.4) exhibited a linearity in the VB₂ concentration range of 0.01 to 0.20 mg L^-1 (r = 0.9993) with a detection limit of 3.2 µg L^-1 (8.6 × 10^-9 mol L^-1). Furthermore, well-resolved reduction peaks of vitamins B₂ and B₉ (VB₉) enabled their simultaneous and selective detection, with linear ranges of 0.01 to 0.20 mg L^-1 for VB₂ and 0.01 to 0.16 mg L^-1 for VB₉. The proposed analytical method, characterized by high selectivity and robustness, was successfully applied in the determination of both vitamins in commercially available dietary supplements, achieving relative errors within -6.2% to 2.7%.