Polyarginine decorated zinc oxide carbon nanotube composite sensor for the voltammetric detection of ferulic acid and hydroquinone

In the present work, the electrochemical detection of ferulic acid (FA) was done using zinc oxide (ZnO) prepared by the application of the green synthesis method in combination with carbon nanotube modified with arginine (PAG/ZnO-CNTCE). X-ray diffraction, scanning electron microscopy, electrochemical impedance spectroscopy and energy-dispersive X-ray spectroscopy were applied for the morphological and structural analysis of prepared ZnO nanoparticles, ZnO carbon nanotube composite electrode (ZnO-CNTCE), and polyarginine modified electrode, PAG/ZnO-CNTCE. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were successfully applied for electrochemical charac­terization and sensitive detection of FA under optimum conditions of pH, accumulation time, accumulation potential, and scan rate with the transfer of two electrons and two protons. The limit of detection of 0.08 and 0.404 μM, respectively, was obtained for CV and LSV in the wide range of 0.4 to 10.0 μM and 0.2 to 10.0 μM. The limit of quantification was found to be 0.274 and 1.348 μM for CV and LSV. The simultaneous analysis confirmed the selectivity of the electrode towards FA in the presence of hydroquinone at two different potentials. The developed PAG/ZnO-CNTCE exhibited excellent reproducibility, stability, repeatability, and anti-interferent properties. FA was successfully detected at the surface of PAG/ZnO-CNTCE with an impressive recovery rate for both popcorn and corn powder samples.