Acetaminophen and Thiosalicylic Acid Sensor Based on Carbon Paste Electrode Modified with Multi-Walled Carbon Nanotubes and Natural Deep Eutectic Solvent

A carbon paste electrode (CPE) modified with multi-walled carbon nanotubes (MWCNTs) and natural deep eutectic solvent (NADES) was prepared and applied for the simultaneous voltammetric determination of acetaminophen (ACP) and thiosalicylic acid (TSA) in real samples. Electrochemical impedance spectroscopy (EIS) was applied for investigation of electron transfer rate of [Fe(CN)₆]^3-/4- as a redox couple probe on the MWCNTs/NADES/CPE surface. The modified electrode preserved and combined the properties of individual modifiers synergistically. Significant enhancement in the peak current responses of ACP and TSA were observed at the modified electrode compared to the bare electrode. Under the optimal conditions, a linear dynamic range of 5–2900 μM for ACP and 5–2250 μM for TSA was obtained. The limit of detection (LOD) for ACP and TSA were 4.71 μM and 4.35 μM, respectively. Finally, this method was successfully employed for the determination of ACP and TSA in real samples.