A screen-printed carbon electrode modified with a green synthesized gold nanoparticle for selective detection of nitrite in drinking water sample

Nanomaterials are used in numerous applications such as medicine, environmental remediation, food packaging, and biomedical applications. Nanoparticle synthesis using the eco-friendly technique shows a fascinating property compared to conventional chemical route methods. In this work, we demonstrate an eco-friendly synthesis of gold nanoparticles (AuNPs) using the Acacia nilotica leaf extract. AuNPs modified screen-printed electrode was applied for electrochemical detection of nitrite. Synthesized AuNPs were characterized by various techniques, including FT-IR, XRD, FE-SEM, TEM, EDX, and UV–visible analysis. FT-IR result of AuNPs demonstrate the distinct functional groups involved in the formation of AuNPs. FE-SEM confirms the AuNPs towards agglomeration and tiny nanoparticles were obtained in uniformly spherical in shape. The TEM analysis revealed AuNPs have small spherical nanoparticles with a size ranging from 10 to 20 nm and EDX result displayed the presence of Au element. The UV–visible absorbance band appeared at 584 nm due to surface plasmon resonance, which confirms the reduction of Au ions to elemental AuNPs. At optimized conditions, a wide linear response range from 0.1 to 1000 μM and a relatively low detection limit (0.03 μM) was observed for electrochemical detection of nitrite ion by modified AuNPs/SPCE electrode. Moreover, the sensor demonstrates outstanding repeatability, selectivity, reproducibility, and storage stability. Thus, the fabricated, AuNPs/SPCE electrode has versatile, practical applications for detecting nitrite in aquatic media.