Novel electrochemical detection of diltiazem in the presence of amlodipine and acetaminophen using a NiZn MOF/rGO modified carbon paste electrode

Abstract

This study focused on the creation of a novel electrochemical sensor by modifying a carbon paste electrode (CPE) with a composite material consisting of reduced graphene oxide (rGO) and a bimetallic nickel‑zinc metal-organic framework (NiZnMOF/rGO) to improve the sensitivity of diltiazem (DTZ) detection. Multiple characterization techniques, including Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and X-ray diffraction (XRD), were utilized to conrm the successful synthesis of the NiZnMOF/rGO nanocomposite. The utilization of electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) revealed a substantial enhancement in electrochemical efcacy, characterized by a pronounced reduction in charge transfer resistance from 9170.6 to 5267.9 Ω and a noteworthy increase in peak current from 21.98 μA to 43.58 μA. In an ideal environment (utilizing a 0.1 M phosphate buffer with a pH of 7.0, applying a scan rate of 0.1 V s1, applying a modulation amplitude of 300 mV, and utilizing a step potential of 12 mV), the sensor demonstrated a limit of detection of 2.71 nM within two distinct concentration intervals of 0.009–0.090 and 0.10–10.0 μM. Chronoamperometric analysis indicated that the process was irreversible and primarily diffusion governed, with a diffusion coefcient of 3.21 × 106 cm2/s. The sensor demonstrated outstanding selectivity, allowing the concurrent and distinct detection of DTZ, amlodipine, and acetaminophen. The analysis of real samples, such as pharmaceutical tablets, human plasma, and urine, resulted in recuperation rates ranging from 96.72 % to 107.14 %, thereby afrming the utility of this approach within intricate biological and pharmaceutical matrices. The proposed electrochemical sensor exhibited enhanced sensitivity for DTZ detection and, compared to previously reported methods, offered a wider linear detection range, a lower limit of detection (LOD), and faster analysis without the need for time-consuming pre-concentration steps. The innovative integration of rGO and NiZnMOF, which provides a high surface area and excellent electron transfer capability, enables this performance.