Electrochemical Detection of the Antidiabetic Medication Metformin in Human Urine and Pharmaceutical Tablets Using Boron-Doped Diamond Electrode

The study focuses on the electrochemical properties of metformin (MET) using a boron-doped diamond (BDD) electrode modified with Nafion and explores how the pH levels in electrolytes affect these properties. The modified electrode is assessed through electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and atomic force microscopy (AFM). The Nafion-modified BDD electrode exhibits significantly greater electrocatalytic activities for metformin oxidation compared to the unmodified BDD electrode. A linear relationship with a correlation coefficient of 0.99 was obtained. Detection limits of approximately 200 and 14 nM and quantification limits of 670 and 47 nM were obtained using square wave voltammetry (SWV) and amperometry, respectively. The developed sensor shows good reproducibility and repeatability. It is demonstrated that the sensor can determine metformin in pharmaceutical tablets and human urine spiked with metformin, showing that the presence of uric acid (UA) does not interfere. The sensor has the potential for use in quick point-of-care testing, providing an alternative to laboratory-based methods and reducing the time and cost of analysis.