Improving gallic acid detection in plant samples: Fabrication and optimization of a sensitive and selective NiO-supported carbon paste electrode

Abstract

In this study, we successfully prepared a modified nickel oxide (NiO) carbon paste electrode to detect gallic acid (GA). NiO nanoparticles were synthesized by the simple, organic solvent-free chemical coprecipitation method, and the electrochemical properties of the electrode and GA were thoroughly investigated using CV, SWV, and EIS, while morphological properties were examined using ICP-OES, TEM, SEM, and XRD. Excellent catalytic characteristics are displayed by the developed material which facilitates the interaction of the target with the electrode surface. The obtained electrochemical information showed that the incorporation of NiO nanoparticles to the carbon paste electrode effectively facilitates electron transfer processes and enriches the catalytic response of the carbon paste electrode. The fabricated NiO/CPE sensor showed a satisfactory linear relationship between peak current and GA concentration in the broad range of 0.2–100 μM and 100–200 μM with a low detection limit of 0.04 μM and limit of quantification of 0.12 μM at pH 3 of BRBS as supporting electrolyte. The selectivity of the proposed method was satisfactory, with acceptable stability, considerable repeatability, and accurate reproducibility. Moreover, the good practicability performance could be effectuated at the NiO/CPE sensor for the quantitative analysis of GA in bourtree, walnut, primrose, and chamomile tea samples. The results were compared with the standard DPPH test and statistical processing of the results was performed, which confirmed the excellent agreement between the two methods. The developed method can provide a cost-effective, rapid, selective, and sensitive means for GA monitoring. When compared to other works, the developed technique has a wider linear range and lower LOD and LOQ, which makes this work a very important reference for the highly sensitive analysis of GA in the field of food safety.