Colorimetric sensing of imidacloprid in cucumber fruits using a graphene quantum dot/Au (III) chemosensor

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 Au 3+ ions and the imidazole group of the pesticide toward reduction of Au 3+ to Au 0 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. 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 pests 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 world 2. It has adverse effects on human health. In recent years, 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 residues 3. The MRL and ADI for imidacloprid in cucumbers are set to 1 mg/kg and 0.06 mg/kg of body weight every day, respectively 4. Currently, a variety of methods, such as gas chromatography (GC), liquid chromatography-mass spectrometry (LC-MS), high-performance liquid chromatography (HPLC), the enzyme-linked immunosorbent assay, and electrochemical methods have been employed in the detection of imidacloprid 1. Although these methods are highly accurate, some disadvantages, such as high cost, onerous time requirements, and unreliability for real-time detection make them suitable for rapid measurements. So it is necessary to develop new and reliable methods, such as colorimetric methods, for rapid detection of imidacloprid. Nanotechnology is an interdisciplinary area of research that has grown globally in the last few decades 5. Among nanostructures, graphene quantum dots (GQDs) and gold nanoparticles (AuNPs) have attracted particular attention 6. GQDs are the sheets of graphene with the size of less than 100 nm that have same properties to graphene 7. Recently, GQDs were used as reducing agents for synthesizing metallic nanoparticles in sensor applications. Amjadi et al. 8 applied GQDs as the reducing agent for the construction of a GQD/Ag nanocomposite. Gold nanoparticles are used in produc...

LSPR immuno-sensing based on iso-Y nanopillars for highly sensitive and specific imidacloprid detection

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Starch/Polyaniline Biopolymer Film as Potential Intelligent Food Packaging with Colourimetric Ammonia Sensor

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