A metal organic framework, UiO-66-NH₂, based on a molybdenum Schiff base complex for the efficient electrochemical determination of diphenoxylate

Diphenoxylate, an agonist and opioid agent, is applied to enhance the activity of the circular muscle of the intestine. In this work, we prepared a novel electrochemical sensor for the determination of diphenoxylate based on a modified UiO-66-NH₂ metal-organic framework (UiO-66-NH₂ MOF) using a molybdenum Schiff base complex and NiS nanoparticles (NiSnp) in a carbon paste electrode (CPE). The UiO-66-NH₂ MOF and UiO-66@Schiff-base-Mo were studied through advanced analysis techniques, such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and transmission electron microscopy (TEM), to reveal the inherent characteristics of the material. The results also showed that the morphology and structure of the UiO-66-NH₂ MOF were maintained after surface modification. The electrochemical properties of the proposed modified electrode (NiSnp/MOF@Mo/CPE) were characterized using cyclic voltammetry (CV). Also, a differential pulse voltammetry (DPV) method was employed for diphenoxylate determination with NiSnp/MOF@Mo/CPE. A linear range was achieved from 1.0 to 55.0 μM and 65.0 to 125.0 μM, and the detection limit was found to be 0.34 μM. The capability of the fabricated sensors based on NiSnp/MOF@Mo/CPE was investigated through diphenoxylate determination in real samples.