Polyaniline-modified cobalt oxide nano-flowers for efficient electrochemical detection of nitrite

In this work, a modified electrode containing a conducting polymer (polyaniline) with Co₂O₃ nanoflowers (NF) was constructed for efficient nitrite detection. The as-prepared GC/Pani/Co₂O₃-NF was characterized using various analytical techniques, including Infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and thermal analysis (TGA/DTA) to ascertain the Co₂O₃'s chemical composition and surface morphology. Furthermore, the electrode's activity toward nitrite detection was studied in a broad pH range, from 2 to 10. The linear detection range and limit were found using the amperometry approach. The GC/Pani/Co₂O₃-NF modified electrode displayed a linear detection range at (10-150) µM and (200-750) µM. In addition, the limits of detection, LOD, for low and high concentrations were 5.565 and 44.98 µM, respectively. While the limits of quantitation (LOQ) were 18.55, and 149.9 µM for low and high concentrations, respectively. Additionally, the kinetic properties of nitrite in different mediums were studied, including diffusion and transport coefficients. Moreover, the electrochemical impedance technique (EIS) measures the charge transfer resistance in nitrite detection upon a modified surface at various pH levels. Also, the electrode's anti-interfering properties were evaluated on a range of compounds such as (l-aspartic acid, l-methionine, l-asparagine, l-lysine, l-glutamic acid, sodium chloride, potassium chloride, glucose, and vitamin C). Antibacterial activity of polyaniline and cobalt oxide was examined to determine the biological activity. Finally, a real sample was used to test the electrode's activity (response time 4 s).