tA new electrochemical sensor for sensitive and selective detection of vitamin B12 (VB12) was constructedby the electropolymerization of pyrrole (Py) in the presence of ferromagnetic nanoparticle-incorporatedtriazine dendrimer (FMNPs@TD) on a gold electrode (Au). The gold/polypyrrole/ferromagnetic nanoparti-cles/triazine dendrimer (Au/PPy/FMNPs@TD) electrode showed electrocatalytic activity for the reductionof VB12 in Britton-Robinson buffers. The performance and interaction of the Au/PPy/FMNPs@TD withVB12 were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS),differential pulse voltammetric (DPV), UV–vis spectroelectrochemistry, and density functional theorycalculations. The resulting sensor exhibited excellent performance for determination of VB12 with a widelinear range (2.50 nM–0.5 M), highly reproducible response (RSD of 2.3%), low percentage of interfer-ences, and long-term stability. The limit of detection (LOD) and limit of quantitation (LOQ) values forthe determination of VB12 were 0.91 and 3.00 nM, respectively. The electron transfer rate constants (ks),charge transfer coefficient (), surface concentrations of electroactive species (), and disproportiona-tion equilibrium constant (KD) for Au/PPy/FMNPs@TD-modified electrodes were calculated. Finally, theconstructed sensor was applied to the determination of VB12 in food samples.
