An Electrochemical Pre-activation Strategy for the Recognition and Determination of Nitroaniline Isomers Based on NiO Nanoparticle-Loaded Carbon Spheres

Nitroaniline isomers, including 2-nitroaniline (2-NA), 3-nitroaniline (3-NA), and 4-nitroaniline (4-NA), pose significant environmental and health risks due to their high toxicity and carcinogenicity. Therefore, developing a reliable method for their qualitative and quantitative detection is crucial. However, their structural similarity presents a challenge, particularly for electrochemical approaches. This paper proposes an electrochemical pre-activation strategy for the selective recognition and determination of nitroaniline isomers using a glassy carbon electrode modified with NiO nanoparticle-loaded carbon spheres (NiO NP-CSs/GCE). Electrochemical analysis demonstrates that NiO NP-CSs exhibit excellent sensitivity toward nitroaniline isomers. Notably, nitroaniline derivatives (nitrosoaniline), formed through electrochemical pre-activation, display distinct reduction peaks, enabling effective isomers differentiation. Furthermore, the reduction peak currents of all three isomers show a linear response over the concentration range of 0.5–600 μM with limits of detection (LODs) in the nanomolar range. The NiO NP-CSs/GCE sensor also exhibits good stability, anti-interference properties, and practical applicability for nitroaniline detection. This work not only introduces an electrochemical pre-activation approach for nitroaniline isomers analysis but also offers a promising strategy for identifying other toxic nitroaromatic compound isomers in environmental monitoring.