Enhancing the electrochemical sensitivity of hydroquinone using a hydrophobic deep eutectic solvent-based carbon paste electrode.

The present study reports the synthesis and characterization of hydrophobic deep eutectic solvents (HDES) based on fatty acids and tetrabutylammonium bromide (TBAB) or 1-octanol using Fourier transform infrared spectroscopy, and the analysis of the physicochemical properties (viscosity, density, electrical conductivity, and water content) of these solvents. A carbon paste electrode modified with 6.0% (m/m) decanoic acid and TBAB-based HDES was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. The oxidation peak currents of the proposed electrode were enhanced by its high electrochemical activity, fast electron transfer rate, and high surface area, while a remarkable decrease was observed in the peak potential separation. The electrochemical determination of hydroquinone (HQ) was carried out using square-wave adsorptive anodic stripping voltammetry (SWAdASV). The electrode response was found to be linear in the HQ concentration range of 2.5 × 10-3.0 × 10 mol L, with the limit of detection (LOD) of 7.7 × 10 mol L. The method was successfully applied for HQ determination in dermatological creams.