Colorimetric Determination of Diazinon in Environmental Water Samples Based on Sensitive Localized Surface Plasmon Resonance of Silver Nanoparticles

Determination of organophosphorus pesticide diazinon (DZ) in water was described based on localized surface plasmon resonance of citrate-capped silver nanoparticles (CC-Ag NPs) in this study. The surface plasmon resonance band was scanned by UV–visible spectrophotometer and Transmission Electron Microscopy (TEM) was employed to reveal the interaction, surface characteristics, and particle size. With adding DZ to the CC-Ag NPs, it was adsorbed onto silver nano-spheres in an aqueous solution and the color of the silver nanoparticles changed from light yellow to orange or brown depending on DZ concentration. As a result of aggregation, the absorption peak of silver nanoparticles around 393 nm decreased and a new peak appeared in 520 nm. The wavelength and intensity shifts were characteristic of the pesticide structure and concentration, respectively. The interaction between the sensor and the pesticide was a result of the soft metal surface binding to the soft sulfur atom of the pesticide. Under optimized conditions, a linear relationship between DZ concentration and the absorbance ratio of A520/A393 and the limit of detection was found in the range of 2- 80 µM and 0.12 µM, respectively. The present method has good repeatability reproducibility and good stability. The proposed method was used for real water samples and the results are in good agreement with other methods of analysis.