Assessing the sensing performance of Voltammetric, Amperometric and Impedimetric methods toward the detection of the antihypertensive drug valsartan using a tin-based non-enzymatic sensor

Abstract

In analytical chemistry, the development of effective techniques for the quantification of organic molecules is of great interest. In this paper we evaluate the adaptation of electrochemical techniques i.e. cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) for the detection of anti-hypertensive drug Valsartan (Val). Sn/SnO₂NP-film modified electrode was fabricated via an electrochemical route, and characterized using both electrochemical (OCP and EIS) and physicochemical (XRD, SEM-EDS, Raman, ATR-FTIR and XPS) techniques. Furthermore, several electrochemical parameters were calculated and evaluated to fully understand the interfacial reaction with Valsartan and the detection mechanism, including catalytic rate constant (K_Cat = 4.90 × 10³ M⁻¹ s⁻¹) and diffusion coefficient (D = 6.71 × 10⁻⁶ cm² s⁻¹). The non-enzymatic sensor was then used for the detection of Valsartan, based on signal to noise ratio (S/N = 3), the response was found to be satisfactory in compared with other works, with detection limits (LOD) as follow: 1.78 μg mL⁻¹ for CV, 0.90 μg mL⁻¹ for EIS and 0.14 μg mL⁻¹ for CA. Low detection limits can be attributed to the unique multi-layer structure that provides a good synergetic effects and enhance active surface area of Sn/SnO₂NP-film, on one hand, and to the good sensitivity provided by the electrochemical techniques, on the other hand. To further highlight and confirm the detection mechanism of valsartan, we have performed a computational study using Density Functional Theory (DFT). Theoretical results of adsorption energy, dipole moment, and gap value confirm that the formed complex presents appealing properties for detection.