Electrochemical sensor based on cobalt oxide-modified screen-printed carbon electrodes for hydrochlorothiazide detection in pharmaceutical formulation

Hydrochlorothiazide (HCT), a widely used thiazide diuretic, faces detection challenges due to low sensitivity, interference, and complex analysis methods. This study explores an innovative electrochemical sensor based on cobalt oxide-modified screen-printed carbon electrodes (CoO/SPCE) to enhance HCT detection. CoO was electrodeposited onto SPCE, optimizing parameters like the CoO concentration and electrodeposition time through cyclic voltammetry. Microscopic analysis confirmed smoother CoO/SPCE surfaces, indicative of improved structural integrity. The modified electrode demonstrated an oxidation peak at 0.242 V with a current of 5.8 μA for HCT, outperforming unmodified electrodes. Electrochemical impedance spectroscopy revealed a 495-fold decrease in charge transfer resistance after modification, underscoring enhanced electron transfer. The sensor exhibited a low limit of detection, minimal relative standard deviation for signal stability (RSD = 3.38 %), and consistent multi-electrode performance (RSD = 3.32 %). The linear relationship between peak current and HCT concentration, I  = 0.01941c + 0.4319 (R 2  = 0.996), confirms the reliability of the method. This CoO/SPCE sensor offers simplicity and rapid detection, marking a significant advancement for in-field HCT analysis.