A New NH2-MIL-88B(Fe) Enhanced Carbon Paste Sensor: Simultaneous Determination of Dopamine and Phenylalanine

Abstract

The precise monitoring of dopamine, a vital neurotransmitter involved in the regulation of mood, cognition, and motor control, is of great importance. In this context, carbon paste electrodes have attracted considerable attention due to their ease of preparation, cost‑effectiveness, and ability to be modified for enhanced sensitivity and accuracy. In the present study, NH₂‑MIL‑88B(Fe) was synthesized and characterized using fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM) analyses, and subsequently employed to modify a carbon paste electrochemical sensor for the detection of dopamine in human and pharmaceutical samples and in the presence of phenylalanine. The synergistic effect of the synthesized metal– organic framework (MOF) combined with graphite led to a remarkable improvement in sensor performance, providing a wide linear response range from 0.7–100 μM and 100–900 μM, with an exceptionally low detection limit of 0.18 μM for dopamine, indicative of the high performance of the optimized electrode. Kinetic analysis further revealed a transfer coefficient (α) of 0.8 and a diffusion coefficient (D) of 4.3 × 10⁻⁶ cm²/s.