Exploring a green and precise approach based on graphene oxide-cobalt ferrite nanocomposite for detection and quantification of vitamin B9 and antibacterial assessment.

In this study, magnetic cobalt ferrite/graphene oxide (CoFeO/GO) sorbent was synthesized and used in magnetic dispersive micro-solid phase extraction (MD-µ-SPE) combined to spectrofluorometric as a green, precise, and effective method to separate and detect of vitamin B9 in food and biological samples. The structure, morphology and magnetic properties of CoFeO/GO nanocomposite was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-Ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). Four parameters of pH, sorbent dose, temperature, and sonication time were selected as effective variables on the process and optimized by central composite design (CCD). Under optimized conditions, the linear range, limit of detection, intra-day (repeatability) and inter-day (intermediate) precision were obtained 15-750 ng mL, 3.96 ng mL, 3.3-3.8%, and 4.2-4.9%, respectively. The material's antimicrobial potency also evaluated, showcasing notable inhibitory action against both Gram-negative Escherichia coli bacteria, with a zone of inhibition measuring 17.5 mm at the highest concentration, and Gram-positive Staphylococcus aureus bacteria, which displayed a 14.5 mm ZIO at similar concentrations. To the best of our knowledge, this is the first report on using CoFe₂O₄/GO for vitamin B9 extraction and detection. This work introduces a novel, eco-friendly, and effective analytical platform that combines the magnetic properties of CoFeO with the high surface area and functional groups of GO for targeted vitamin analysis. These results demonstrate that the synthesized nanocomposite possesses both excellent adsorption capability and antibacterial activity.