Colorimetric detection of organophosphorus pesticides from food using metal nanostructures

Abstract

XVIII newlineABSTRACT newlineArable lands are decreasing due to the excessive increase in the world s population. Insecticides are playing an effective role in pest management and they are helpful to improve crop productivity. Residual insecticides are dangerous for the health of the human being. Therefore, monitoring of residual insecticide is an important task. Hence, present research work was carried out to detect residual insecticides from the number of food samples using metal nanostructures as a colorimetric probe. Four metal nanostructures viz. iron, copper, silver, and gold were synthesized using co-precipitation method and reduction method, and for surface modification and functionalization of metal nanostructures, organic acids (malic, citric, adipic and tartaric acid), gum arabic, and#946;-cyclodextrin, and dextrose were used in different concentration and ratio. Based on visual color confirmation and UV-Visible spectrum, suitable metal nanostructures as a diagnostic agent were screened out. The dynamic light scattering technique was used for the determination of the particle size and zeta potential and the metal nanostructures with significantly (plt0.05) least particle size were screened out for further analysis. Also, based on targeted crops, six different insecticides viz. Monocrotophos, Chlorpyriphos, Flonicamid, Imidacloprid, Thiamethoxam, and Acetamiprid were selected. For the development of diagnostic agents, all selected metal nanostructures were used as a colorimetric probe for the detection of selected six insecticides. Among all metal nanostructures, gold nanostructures modified with citric and adipic acid (Au:CA:AA 1:2:1) showed promising results for the detection of monocrotophos. The sensitivity of Au:CA:AA (1:2:1) nanostructures were examined by the effect of pH, different concentrations of monocrotophos, and varied concentrations of nanostructures. Also, interference of other insecticides was examined using visual color change confirmation and UV-Visible spectroscopy and it was observed that the diagnostic agent was only sensitive towards monocrotophos. The limit of detection and quantification was also calculated using the obtained standard curve (A640/A539). Three food samples viz. wheat, mustard, guar samples were collected from the agricultural fields of the North India region. Based upon the lowest limit of detection value, isolation of monocrotophos from the wheat, mustard, and guar matrix was optimized. The developed analytical method was also applied to the real food samples for the detection of monocrotophos. As well, the developed analytical method was used for the detection of monocrotophos from different food samples obtained from different farmers. Food samples obtained from the Bathinda region showed high content of monocrotophos as compared to food samples obtained from other regions. newline