Environmentally friendly synthesis of gold nanoparticles at room temperature for chlorpyrifos-methyl detection in water samples

In this study, a facile synthesis of gold nanoparticles (AuNPs) is achieved through an environmentally friendly method in less than 2 min, using ascorbic acid and pentetic acid as reducing and stabilizing agents, under alkaline conditions at room temperature. The effects of the main experimental parameters on the synthesis performance were analyzed using response surface methodology. The obtained particles, spherical in shape and with average size of 9.2 nm, were tested as sensor for determination of chlorpyrifos-methyl (CPM), an organophosphate insecticide widely used in agriculture practices and households, which represent a major concern for the environment and human health. CPM was determined through the changes on the localized surface plasmon resonance (LSPR) band of AuNPs at 527 nm. Under optimal conditions, the method was evaluated in the concentration range between 5.00 and 40.0 μg L^-1, with R² > 0.98, limit of detection of 3.79 µg L^-1 and RSD values lower than 6.5 %. The applicability of this methodology for the analysis of real samples, including river water and well water, was tested with satisfactory recovery values (84.0–––98.8 %). Besides, the practicality and functionality of the proposed method were assessed by the Blue Applicability Grade Index (BAGI), a new metric tool developed in 2023, with an outstanding performance.