Electrochemical Measurement of Noscapine and Lorazepam Using a Carbon Paste Electrode Modified with Multi-walled Carbon Nanotubes and Natural Deep Eutectic Solvent

In the present study, simultaneous voltammetric determination of noscapine (NOS) and lorazepam (LOR) was studied for the first time. A carbon paste electrode modified with multi-walled carbon nanotubes (MWCNTs) and natural deep eutectic solvent (NANADES) (MWCNTs/NADES/CPE) was used for this purpose. Electrochemical impedance spectroscopy (EIS) was applied for the investigation of the electron transfer rate of [Fe(CN)6](3-/4-) as a redox couple probe on the surface of the MWCNTs/NADES/CPE. The modified electrode preserved and combined the properties of the individual modifiers synergistically. A significant enhancement in the peak current responses of NOS and LOR was observed on the modified electrode surface compared to the bare electrode. Under the optimal conditions, the peak current of differential pulse voltammograms was linearly dependent on analyte concentration in the range of 3-1700 µM for NOS and 1-2220 µM for LOR. The limit of detection (LOD) for NOS and LOR was 1.90 µM and 0.69 µM, respectively. Finally, this strategy was also employed for the determination of NOS and LOR in pharmaceutical samples.