Development of a Selective Spectrophotometric Method for Deltamethrin Using Silver Nanoparticles

The present work proposes a spectrophotometric method for deltamethrin determination using silver nanoparticles (AgNPs). The AgNPs are spherical with a diameter of~11 nm and a negative surface charge with zeta potential ranging from −4.1 mV (pH 2) to −48 mV (pH 10). The AgNP colloidal system showed greater stability at higher pH values and for a molar ratio of 6 between the sodium borohydride and silver nitrate in the synthesis. This is because the borate ions from the oxidation of borohydride are present on the surface of the nanoparticles, promoting an electrostatic repulsion between them which keeps them dispersed. The method was validated, obtaining satisfactory results of veracity and precision, and the limits of detection and quantification were 0.17 and 0.51 mg L−1, respectively. The method was selective for deltamethrin compared to the compounds cypermethrin, endosulfan, thiamethoxam, atrazine, chlorpyrifos and parathion. Deltamethrin promotes the formation of dendritic silver nanostructures, changing the color of the system. The results demonstrate the development of a reliable and selective method for the detection of deltamethrin using AgNPs.