Quanhong Ou,Biao Tang,Liqin Jiang,Mingcheng Han,Weiye Yang,Junqi Tang,Gang Liu
Carbosulfan gets easily decomposed into carbofuran and 3-Hydroxy carbofuran in vegetables and forms harmful residues. To detect the residues of carbosulfan in vegetables (for example, cowpeas), a super-sensitive method of surface-enhanced Raman spectroscopy (SERS) was used in this work. Silver sol was prepared as the SERS substrate. To solve the adsorption problem of carbosulfan on Ag nanoparticles, 2, 6-dichloroquinone-4-chlorimide (chromogenic agent), and sodium hydroxide were added in carbosulfan to generate a complex, which was then mixed with the silver sol in the best proportion to examine SERS spectra. According to density functional theory calculations, the spectral peak positions of carbosulfan were determined. The optimal mixing ratio of the complex and the silver sol to obtain the optimal SERS spectrum and the detection limit of carbosulfan were investigated. The ultra-sensitive detection of carbosulfan residues (8.7 × 10 -11 g/L) in cowpeas was realized. The results of this work indicate that SERS is a promising technique for detecting single-molecule pesticide residues in vegetables.
Rapid and accurate detection of carbosulfan residues in vegetables is important for ensuring food safety. Herein, based on the unique hydrolysis behavior of carbosulfan, a nanozyme-based colorimetric sensing platform was proposed for detection of carbosulfan. Hollow polydopamine/MnO 2 nanoparticles (H-PDA/MnO 2 NPs) with excellent oxidase-like activity were synthesized, which can promote the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxidative product (oxTMB). Under acidic conditions, carbosulfan can be decomposed and produce reductive sulfide species (-SH), which are capable to disintegrate MnO 2 NPs, resulting in decreased oxidase-like activity of H-PDA/MnO 2 NPs. Based on the inhibitory effect on oxidase activity of H-PDA/MnO 2 NPs, an acetylcholinesterase-free colorimetric assay was proposed for detection of carbosulfan with low limit of detection of 0.63 ng mL −1 . Integrating test swabs with smartphone, a portable colorimetric sensor was constructed, showing great potential for on-site detection. To demonstrate the feasibility of this method, carbosulfan in real vegetable samples were determined.
Background Carbosulfan (CBS) is a widely used carbamate pesticide in agricultural production, its easy decomposition into hypertoxic carbofuran poses serious threats to human health and food safety. Therefore, sensitive and accurate detection of CBS is of significant importance. Conventional chromatography-based techniques require expensive instruments and complicated sample pretreatment, limiting their application for fast detection. Current electrochemical and colorimetric methods for detection of pesticides based on the cascade catalytic reactions between acetylcholinesterase (AChE) and nanozymes, which exhibit inferior selectivity. Hence, selective, sensitive and fast detection of CBS is still challenging. Results In this work, an AChE-free colorimetric method was proposed for selective detection of CBS based on its unique hydrolysis behavior and nanozyme. Ti 3 C 2 nanosheets/AuPt nanoparticles (Ti 3 C 2 /AuPt NPs) with enhanced peroxidase-like activity were prepared via one-step self-reduction reaction. CBS can be hydrolyzed under acidic condition and produce –SH moieties, which could bond to Pt atoms of Ti 3 C 2 /AuPt NPs and shield the active sites of nanozyme, resulting in decreased catalytic activity. Based on the inhibitory effect on the peroxidase-like activity of Ti 3 C 2 /AuPt NPs, a colorimetric method was proposed for direct detection of CBS. Under optimal conditions, the method showed wide linear range (0.5 ng mL −1 -5 μg mL −1 ), low limit of detection (0.342 nM), good selectivity and anti-interference ability. The feasibility of this method for practical use was confirmed by analysis of CBS in real lake water samples. Significance This work proposed a simple colorimetric method for selective and fast detection of CBS, which avoided employing AChE and cascade catalytic reactions, significantly lowering the detection cost and improving detection efficiency. The method showed great potential for accurate detection of CBS in actual samples, and provided a new avenue for developing nanozyme-based colorimetric method for detection of other pesticide residues.
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