Preparation method and application of imidaclothiz MIP (molecularly imprinted polymer) microspheres

Abstract

The invention relates to the technical field of MIPs (molecularly imprinted polymers), in particular to a preparation method of imidaclothiz MIP microspheres. The preparation method comprises the following steps: methacrylic acid and imidaclothiz are dissolved in a solvent and subjected to ultrasonic treatment, then a crosslinking agent is added, nitrogen is introduced for oxygen removal, sealing and prepolymerization are performed, a prepolymer is transferred into a polymerization reactor, column-layer chromatographic silica gel and an initiator are added, the mixture is oscillated sufficiently, nitrogen is introduced again for oxygen removal, and an obtained mixture is sealed; the sealed mixture is subjected to a reaction in a constant-temperature water bath oscillator, a product is cooled and placed in a refrigerator, excessive hydrofluoric acid is added, an obtained mixture is stirred and filtered, a filtrate is washed and dried, and solid precipitates are obtained; the solid precipitates are subjected to Soxhlet extraction with a mixed solvent, washing is stopped until no imidaclothiz molecule can be detected in washing liquor by a high-performance liquid chromatography-mass spectrometer, and a product is dried to constant weight. The imidaclothiz MIP microspheres are taken as filler of SPE columns, and technical support is provided for monitoring imidaclothiz residue condition of tea and guaranteeing quality safety of the tea.

Description

Technical field [0001] The invention belongs to the technical field of molecularly imprinted polymers, and in particular relates to a preparation method and application of chlorothialine molecularly imprinted polymer microspheres. Background technique [0002] Chlorothialine (Imidaclothiz, CAS 105843-36-5, whose molecular structure is shown in the following formula), is a neonicotinoid systemic insecticide that acts on acetylcholinesterase receptors. Early foreign research on this substance mainly stayed in the laboratory stage. Nantong Jiangshan Pesticide Chemical Co., Ltd. took the lead in commercializing it in China. In October 2002, it obtained the registration of chlorothialine technical and 10% wettable powder. At present, it is registered as a 10% chlorothialine wettable agent on tea trees, and the control object is small green leafhopper. [0003] [0004] Molecular structure of chlorothialine [0005] In June 2017, the National Health and Family Planning Commission, the Mi...

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Problems solved by technology

[0005] In June 2017, the National Health and Family Planning Commission, the Ministry of Agriculture and the Food and Drug Administration jointly issued the national food safety standard "GB2763-2016 Maximum Residue Limits of Pesticides in Food". 490 new items, but the maximum residue of chlorothialine in tea is still the temporary limit of 3mg / kg, because the corresponding national or industry recommended detection method standards have not been formulated

In the detection method research of chlorothialine in relevant crops at present, mainly adopt solvents such as dichloromethane, ethyl acetate, normal hexane to extract, carry out qualitative and quantitative with liquid chromatography-ultraviolet detector or liquid chromatography-mass spectrometry, However, tea contains a large number of uncertain interfering substances. The traditional analysis method has poor purification effect and is easy to contaminate the liquid mass spectrometer. Moreover, the complex matrix in tea interferes with chlorothialine under the ultraviolet detector, which is likely to cause false positives. result

[0006] In recent years, the research on the detection technology of chlorothialine has made some progress, but in practical application, the common disadvantages of these methods are that the pretreatment is complex, cumbersome, time-consuming and costly.

Although solid-phase extraction (SPE) technology is mostly used for the pretreatment of chlorothialine at present, although there are many types of columns, they lack high selectivity, and it is easy to extract the coexisting interfering substances together. For samples with extremely low concentration, the enrichment factor Limited, does not meet testing requirements

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