N-ethyl-2-picolinoylhydrazine carbothioamide (EPHC) as an excellent sensing element for the electrochemical measurement of T4, the free thyroid hormone

This article examines the creation of our innovative electrochemical electrode, and the advantages of the electrochemical approach for accurate monitoring of the thyroid hormone (T ₄ ). The sensor functions through electrochemical interactions between the T₄ molecule and the electrode surface, which includes N-ethyl-2-picolinoylhydrazine carbothioamide (EPHC). By using cyclic voltammetry (CV), differential pulse voltammetry (DPV), or electrochemical impedance spectroscopy (EIS), the sensor delivers dependable and precise results, with prospective applications in free-T ₄ monitoring. EPHC was synthesized and characterized using FT-IR, SEM, and EDX techniques to confirm successful synthesis. EPHC was blended with suitable components to formulate a consistent carbon paste, to which a graphite bare was affixed for electrical connectivity. The sensor demonstrates impressive performance, achieving a low detection limit of 8.0×10 ^− 3 µM. It operates effectively across a linear range from 8.7×10 ^− 3 to 80.0 µM. The response time is rapid at 30 seconds. The electrode exhibits satisfactory repeatability and reproducibility. The sensitivity for T ₄ is measured at 1.17 µA/µM, reflecting the sensor’s strong analytical capability. The sensor successfully quantified free-T ₄ in different real matrices, under optimized conditions of a pH of 9, a scan rate of 80 mV/s, 5.0 mg of EPHC, and 0.5 g of graphite powder.