Study Of Sample Pretreatment Methods For Sulfonylurea Herbicides Residues Analysis In Complex Samples

In recent years, sulfonylurea herbicides are widely used for the control of weeds in agriculture crops because of their low application rates, low toxicity to mammals and unprecedented herbicidal activity. However, sulfonylurea herbicides are used for the control of weeds at the same time effectively, also cause environmental pollution and human health damageable such as cancer.Therefore, to establish a rapid, accurate, and efficiency methods for determination trace sulfonylurea herbicide have been the attention of scientific research workers.Pesticide residue analysis have characteristics of variety, complex composition, morphological diversity and low concentration, so samples need to be pre-proceed before instrumental analysis usually. Sample analysis process includes sample collection, sample pretreatment, analysis, data processing and reporting results, the sample pretreatment accounted for two-thirds in the entire analysis time, and almost ninety percent of the errors come from sample pretreatment. Therefore, sample pretreatment in food safety analysis and detection, especially for trace pesticide residues has become one of the most important research areas in modern analytical chemistry.In this study, new methods based on UAE-DSPE and MSPD-DLLME combined with high performance liquid chromatography had been developed for the determination of sulfonylurea herbicides in complex samples such as fruit juice, food crop and tea. The main research contents are as follows:1. The pretreatment method of ultrasound-assisted extraction (UAE) combined with dispersive solid-phase extraction (DSPE) and high performance liquid chromatographic (HPLC) was developed for determination of two sulfonylurea herbicides in fruit juice. The experimental conditions for the UAE-DSPE were optimized, and then the proposed method can meet the requirements for simultaneous determination of sulfonylurea herbicides in fruit juice.2. The method based on matrix solid-phase dispersion (MSPD) extraction for determination of four sulfonylurea herbicides in food crop has developed. The main parameters that affect extraction yield, such as:dispersant, type and amount of additives clean-up sorbent, extractive solvent and acid strength were optimized, and then the proposed method is applicable to the efficient determination of four sulfonylurea herbicides in food crop.3. The new method based on matrix solid-phase dispersion (MSPD) combined with dispersive liquid-liquid microextraction (DLLME) and high performance liquid chromatography for simultaneous determination of the four sulfonylurea herbicides in tea has developed. The experimental conditions for the MSPD-DLLME were optimized. The results showed that matrix solid-phase dispersion combined with dispersive liquid-liquid microextraction was a very simple, fast, sensitive, reliable and efficient analytical method for determination of sulfonylurea herbicides in tea.