Electrochemical characterization of naproxen and the adsorbed naproxen oxidation products at glassy carbon electrode modified with carboxyl functionalized multi-walled carbon nanotubes and introducing a new route for naproxen determination

In the present work, a glassy carbon electrode was modified with carboxyl functionalized multi-walled carbon nanotubes (f-MWCNTs) to investigate the electrochemical behavior of naproxen (NAP) and the adsorbed NAP oxidation products (NAPop) for the first time. Cyclic and linear sweep voltammetry techniques were used for the electrochemical investigation of NAP and the adsorbed NAPop. The results showed that the mechanisms of the oxidation reaction of NAP and the redox reaction of the adsorbed NAPop were irreversible and reversible surface-controlled processes, respectively. Then, an indirect method was applied for the determination of NAP with a focus on the adsorbed NAPop. Programmed linear sweep voltammetry (LSV) was performed, and two linear relationships were observed between the peak current intensity of LSV responses of the adsorbed NAPop and the concentration of NAP in the range of 0.0–30.0 µM and 30.0–250.0 µM. The limit of detection and limit of quantification for NAP determination based on S/N = 3 and S/N = 10 were calculated to be 2.0 and 6.8 µM, respectively. The effect of the presence of some potent interfering compounds was examined, and the developed method was applied for the determination of NAP in tap water and NAP tablet samples with satisfactory results.