An Electrochemical Sensing Platform Based on a Boron-Doped CaO/Zinc-Based MOF-5 Carbon Matrix for Nitroaromatic Explosive 2,4-Dinitrotoluene in Food, Soil, and Water Samples

The dinitroaromatic compound 2,4-dinitrotoluene (2,4-DNT) is a commonly utilized intermediate in the manufacture of explosives and various other industrial processes. Its discharge into the environment poses major health concerns to people. Consequently, it is essential to develop quick, accurate, and sensitive detection methods for environmental monitoring. We report the development of a highly sensitive electrochemical sensor (ECS) for the sensing of 2,4-DNT based on advanced nanostructured materials. The zinc-based metal–organic framework-5 (Zn-MOF-5) and boron-doped calcium oxide (B-CaO) were synthesized using facile methods and characterized employing multiple analytical methods to confirm the morphology, crystallinity, and elemental composition. These nanostructured materials were integrated into a modified carbon paste electrode (CPE) to enhance EC performance through increased surface area and improved conductivity. EC measurements demonstrated efficient electrocatalytic reduction of 2,4-DNT with distinct reduction peaks associated with nitro functional groups. Electrochemical characterization of the fabricated sensor was carried out using cyclic voltammetry (CV), square wave voltammetry (SWV), amperometry, and electrochemical impedance spectroscopy. The developed nanocomposite showed a linear response over the concentration range of 1.0–80.0 μM, excellent analytical performance, high sensitivity, and low detection limits of 9.9 × 10 –8 M (peak 1) and 6.9 × 10 –8 M (peak 2). SWV measurements revealed high sensitivity and efficient electrocatalytic reduction of 2,4-DNT with distinct reduction peaks associated with its nitro functional groups. The nanocomposite sensor B-CaO/Zn-MOF-5/CPE showed strong selectivity toward 2,4-DNT in the presence of common interfering species. Furthermore, the sensor demonstrated successful detection of 2,4-DNT in food, soil, and water samples, highlighting its practical applicability for environmental monitoring and safety-related analyses. The proposed platform offers a sustainable and cost-effective scheme for the development of advanced ECS for nitroaromatic explosive contaminants.