Preparation Of Chlorsulfuron Molecularly Imprinted Polymers, Chlorsulfuron And Metsulfuron-Methyl Imprinted Polymers Application In The Residues Analysis

Sulfonylurea herbicides are among the pesticides intensively used as a pre-and post-emergence controller of grassy weeds in farmland, which include monosulfuron, bensulfuron-methyl and metsulfuron-methyl, chlorsulfuron and so on. Sulfonylurea herbicides have been employed to protect crops (e.g. rice, barley, soybean, wheat and maize) from weed and insect attack. However, over-usage of the artificial chemical has caused seriously environmental problems. Hence, it is of great importance to monitor its residue in soils and quantify its contamination to crops. Currently, a series of methods such as C18solid phase extraction, soxhlet extraction, liquid-liquid extraction, thin layer chromatography and column chromatography are used to pre-treat sulfonylurea-herbicide and its residue. However, these methods have several inherent limitations such as time-consuming sample pre-treatment, consumption of organic solvents and requirement of costly equipments.In this study, we synthesized the MIP using chlorsulfuron as the template molecule. The molecularly imprinted solid phase extraction cartridges were prepared to extract and enrich the residues of chlorsulfuron in soil, wheat and aqueous samples. The purpose of our study was to provide a method that can comprehensively analyze the herbicide at trace abundance in multiple media. The major topics in the thesis include:1. A molecularly imprinted polymer (MIP) was prepared using chlorsulfuron (CS), a herbicide as a template molecule, methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linker, methanol and toluene as a porogen, and2,2-azobisisobutyronitrile (AIBN) as an initiator.2. The equilibrium adsorption experiments were carried out to investigate the affinity and selectivity of chlorsulfuron, sulfonylurea and other herbicides. In this article, we study the interaction of chlorsulfuron and MAA in solution by UV absorption spectra. The results of the binding characteristics of the imprinted polymer and the Scatchard analysis showed that molecularly imprinted polymer has good retention effects on template, and the different binding sites may be the result of the coordinative ratio of different imprinting molecular with functional monomer and the non-uniform binding sites of imprinted polymer in polymer solution. The binding behaviors of the template chlorsulfuron and its analogues on MIP were evaluated by equilibrium adsorption experiments, which showed that the MIP particles had specific affinity for the template CS.3. Solid phase extraction (SPE) with the chlorsulfuron molecularly imprinted polymer (CS-MIP) as a adsorbent was investigated, and the optimum loading, washing and eluting conditions for chlorsulfuron molecularly imprinted polymer-solid phase extraction (CS-MISPE) were established. The optimized CS-MISPE procedure was developed to enrich and clean-up the chlorsulfuron residue in water, soils and wheat plants. Finally, concentrations of chlorsulfuron in the samples were analyzed by HPLC-UVD. The average recoveries of CS spiked standard at0.05～0.2mg L-1into water were90.2～93.3%, with the RSD being2.0～3.9%(n=3). The average recoveries of1.0mL CS spiked standard at0.1～0.5mg L-1into10g soil were91.1～94.7%, and the RSD was3.1～5.6%(n=3). The average recoveries of1.0mL CS spiked standard at0.1～0.5mg L-1into5g wheat plant were82.3～94.3%, with the RSD being2.9～6.8%(n=3). Overall, our study provides a sensitive and cost-effective method for accurate determination of CS residues in water, soils and plants.4. Solid phase extraction (SPE) with the metsulfuron-methyl molecularly imprinted polymer (MSM-MIP, nano) which was prepared by Nanjing Medical University as a adsorbent was investigated. The optimized MSM-MISPE procedure was developed to enrich and clean-up the metsulfuron-methyl residue in water, soils and rice grain. Finally, concentrations of metsulfuron-methyl in the samples were analyzed by HPLC-UVD. The spiked concentration was0.5mg·L-1,0.2mg·L-1and0.1mg·L-1. The average recoveries of water were89.8～91.1%, with the RSD being1.6～3.6%(n=3), the average recoveries of soil were89.2～92.3%, with the RSD being1.5～3.5%(n=3), the average recoveries of water were89.3～94.8%, with the RSD being2.0～5.8%(n=3).