Abstract
The current research presents a very simple method for the colorimetric detection of imidacloprid using a graphene quantum dot/Au (III) chemosensor. The results demonstrated that there is an interaction between Au3+ ions and the imidazole group of the pesticide toward reduction of Au3+ to Au0 in the presence of graphene quantum dots. This phenomenon changes the color of gold nanoparticles from yellow to grey or red, and causes a shift in the peak of localized surface plasmon resonance (LSPR) as gold nanoparticles are formed or aggregated based on the concentration of imidacloprid. Imidacloprid was determined by the developed sensor in a linear area of 0.01–1 ppm with a detection limit of 0.007 ppm. Therefore, a simple, quick, and sustainable sensor has been developed for the determination of the investigated analyte. Moreover, the sensor was applied to determine imidacloprid in the real cucumber samples fairly successful.
Highlights
Insecticides have a vital role in protecting plants from insects and pests
The absorption spectrum of the graphene quantum dots (GQDs) solutions in water indicated two distinct absorption peaks (Supplementary Fig. S1): a main peak at the wavelength of 400 nm and a shoulder at 340 nm; these are the peaks of GQDs which are related to the π–π* and the n–π* electron transitions of C=C and C=O bonds, respectively[8]
We demonstrated that a GQD/Au3+ sensor can recognize the presence of imidacloprid in standard and real cucumber samples by the formation of AuNPs, which change the color of the solution
Summary
Insecticides have a vital role in protecting plants from insects and pests. Neonicotinoid insecticides are increasingly being replaced by organophosphorus and carbamate pesticides to control sucking p ests[1]. Within the neonicotinoid pesticide group, imidacloprid (N-{1-[(6-chloro-3-pyridyl)methyl]-4,5-dihydroimidazol-2-yl}nitramide) is the second pesticide in terms of popularity in the w orld[2] It has adverse effects on human health. The excessive use of pesticides has caused an increase in their residues in agricultural products, especially in greenhouse products such as cucumber and tomato For this reason, acceptable daily intakes (ADIs) and maximum residue levels (MRLs) were established by international organizations as the criteria to prevent the adverse health effects of pesticide r esidues[3]. AuNPs were used in the area of pesticide detection, especially in agricultural crops Some N-heterocyclic compounds, such as imidazole and tetrazole, which are called ligands, readily donate electrons in the formation of organometallic complexes These complexes have shown particular use in the construction and stabilization of AuNPs13. It is important to mention that AuNPs are solely formed by adding a reductant in solutions that include an imidazole-containing polymer and imidazolium-based ionic liquids
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