Eco-conscious and cost-effective electrochemical sensor for selective determination of eszopiclone in pure form, alkaline-stressed samples, and pharmaceutical tablets

Abstract

A novel, rapid, economic, and environmentally friendly voltammetric method using a pretreated pencil graphite electrode (PPGE) was employed for eszopiclone (EZP) determination in its pure form, tablet formulation, and in the presence of its alkaline degradants using differential pulse (DPV) and square wave (SWV) techniques. The impact of both potentiostatic and potentiodynamic pretreatment strategies on the electrode analytical performance was investigated. The PPGE exhibited superior electrocatalytic activity compared to the non-pretreated pencil graphite electrode (NPGE) and the glassy carbon electrode (GCE). Moreover, the influence of surfactant addition on the peak current was studied. The use of sodium dodecyl sulfate (SDS) surfactant enhanced the concentration range of measurements to 2.5–300 µg mL⁻¹ with a limit of quantitation (LOQ) of 2.443 µg mL⁻¹ and a limit of detection (LOD) of 0.733 µg mL⁻¹. A further sensitivity enhancement was achieved using the differential pulse adsorptive stripping voltammetric (DP-AdSV) technique, extending the linear concentration range to 0.25–15 µg mL⁻¹ with a LOQ of 0.195 µg mL⁻¹ and a LOD of 0.058 µg mL⁻¹. The PPGE was successfully characterized using scanning electron microscopy, X-ray diffraction, and Fourier transform infrared. The method was rigorously validated as per ICH guidelines and its environmental sustainability was quantitatively assessed using the Analytical Eco-Scale and the Green Analytical Procedure Index (GAPI). Furthermore, the method's overall “whiteness” was assessed using the recently released Red-Green-Blue (RGB) 12 model approach, reflecting the balance between analytical performance, environmental impact, and practical applicability.