Mechanochemical Synthesis of Graphene Oxide/UiO-66-NH₂ Nanocomposites: Characterization and Fabrication of an Electrochemical Sensor for the Determination of Tetracycline Residues in Milk Samples

This paper describes a green mechanochemical approach for the synthesis of a graphene oxide-based UiO-66-NH₂ metal organic framework composite (GO/UiO-66-NH₂) for the fabrication of a sensitive electrochemical sensor for the determination of tetracycline (TC) residues in milk samples. The structural and electrochemical characteristics of the GO/UiO-66-NH₂ nanocomposite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), FT-IR spectroscopy, and cyclic voltammetry (CV). Incorporation of UiO-66-NH₂ onto the GO surface can increase the number of effective reaction sites and improve the electrochemical performance of the fabricated sensor. The sensor was simply prepared through drop-casting a GO/UiO-66-NH₂ suspension onto the glassy carbon electrode surface and used for TC determination by differential pulse voltammetry (DPV) as a sensitive analytical method. The fabricated sensor provided a linear calibration over the concentration ranges of 0.02-1.00 μg mL^-1 (<i>R</i> ² = 0.9921) and 1.00-40 μg mL^-1 (<i>R</i> ² = 0.9932) with a limit of detection of 0.003 μg mL^-1 using DPV. The proposed sensor was successfully applied to measure the TC residues in different milk samples with satisfying recovery from 94.0 to 105.0%.