A facile and sensitive detection of organophosphorus chemicals by rapid aggregation of gold nanoparticles using organic compounds

Organophosphorus (OP) chemicals are highly effective insecticides and germicides, and are the most widely used in agriculture. Unfortunately, OP compounds are some of the most toxic substances to humans, even at very low doses. Because detecting OP residues in agricultural products is essential, simple, sensitive, and particularly rapid on-site detection methods are required. Gold nanoparticles (AuNPs) have been used as signal-enhancing detection probes in the field of biosensors due to their size-dependent optical properties. When imidazole was added to AuNPs mixed with OP compounds, the AuNPs was aggregated and their color changed to purple. This caused the appearance of a new peak at 660-670 nm, which could be measured within approximately 30 s. Therefore, this method allows the detection of OP compounds, including diazinon, iprobenfos, and edifenphos, on-site at part-per-billion (ppb) concentrations, and also affords a straightforward method. Furthermore, the method was successfully applied in the determination of OP compound in a real sample (river water) with satisfactory results.