Review on rapid detection of pesticide residues in agricultural and food products

Abstract: Pesticides were widely applied to eliminate or control a variety of agricultural pests and diseases. However, they exhibited acute or chronic toxicity on human health through their residues in agricultural product and food. Thus, monitoring pesticide residues was extremely crucial to ensure that pesticides in agricultural products were in permitted levels. The identification and quantification of pesticides were generally based on mass spectrometry combined with gas and/or liquid chromatography, or capillary electrophoresis. However, these methods involved large and expensive instruments, time-consuming sample preparation and trained personnel. Therefore, it was important to set up onsite assays and techniques, especially highly sensitive and selective, simple, efficient, and cost effective ones for rapid detection of pesticide residues. This review summarized the application of fast analytical methodologies such as enzyme inhibition assays (EIA), immunoassays, optical spectroscopy assays and various biosensors in the analysis of pesticide residues in agro product and food in the past few years. EIA was widely used for rapid colorimetric or spectrophotometric screening of pesticides in China, which was based on the inhibition of cholinesterase (ChE) activity by organophosphate and carbamate. Immunoassays, such as enzyme-linked immunosorbent assay (ELISA), were quantitative or qualitative methods of analysis for a substance, which took antibodies as the analytical reagents. Immunoassays depended on the use of an analytical reagent that was associated with a detectable marker, such as enzyme, fluorescence, chemoluminescence radioactive element, and so on. Colloidal gold-based immunoassay was proven to be fast, sensitive and cost-effective for pesticide detection. Biosensors were analytical devices, used for the detection of analytes, which combined a biological component with a physicochemical detector. The development of biosensors for pesticides was also an active research area, which offered great advantages over conventional analytical techniques. Aptamers were shown as good candidates to replace the conventional antibodies in more robust and stable biosensors for pesticide detection. Optical spectroscopy assays, including visible/near-infrared, Roman, and Tera Hertz time-domain spectroscopy, had pollution-free and lossless nature, which were regarded as potential methods for qualitative and quantitative analyses of pesticides. The basic principles of these fast screening strategies were discussed, and both advantages and drawbacks of these techniques were then summarized. Special emphasis was placed on the state-of-art techniques including nanobiotechnology, molecular imprinting technique (MIT) and microfluidics, because of their great potential in pesticide residue analyses. Nanomaterials including carbon nanotubes (CNTs), quantum dots and nanoparticles were developed to improve the performance of pesticide detection. MIT, as a burgeoning powerful technology, was gaining increasing attention for its prospect of creating synthetic polymers with highly specific recognition capabilities in complicated samples. Furthermore, the future perspectives and the trends for pesticide residue analysis were also presented. Most studies were focused on the detection of insecticides, which were used in very large quantities. In future, it is necessary to pay more attention to the detection of other families of pesticides with lower mammalian toxicity, such as herbicides and plant growth regulators. The miniaturization and integration, multi-channel detection, wireless communication, higher stability and repeatability of the detection instruments are the development direction of pesticide residue detection in the future.