Application Of Novel Liquid-phase Microextraction Technique In The Residue Analysis Of Pesticide In Complex Samples

In recent years, the pesticide is extensively used for agricultural production in order to improve the output rate of the crops, the most commonly including the herbicides and the fungicides. As an important class of broad-spectrum herbicide, sulfonylurea herbicides are widely used in agricultural production due to their high selectivity and very low dosage rates. Strobilurins are a new class of synthetic fungicides, which have a novel mode of action and are very safe from an environmental point of view. They are widely used in agricultural production in order to control the powdery mildew and scab in crops due to their outstanding advantages of high herbicidal activity, high selectivity and very low dosage rates.However, due to the high usage of pesticides, they may have a certain amount of residue in crops.which would will bring a potential threat to the food safety and public health, and cause by certain adverse effects to the environment. Therefore, it is necessary to establish a simple, rapid and accurate method to determine the pesticide residues in crops.Liquid phase microextraction technology is a new type of pretreatment technology based on the liquid-liquid extraction, which is significantly better than LLE. Ultrasound-assisted emulsification microextraction is a new type of liquid-phase microextraction technology. It has a high extraction efficiency, a good enrichment factor, a simple operation, a low cost, and do not need to join a dispersing agent in order to effectively reduce the environmental damage.Based on ultrasound-assisted emulsification microextraction, this paper has developed some new methods to detect herbicide and fungicide residues in Orange samples and optimized the extraction conditions which can affect the extraction efficiency. Main contents and results are as follows:1. USAEME coupled to HPLC-UV was developed to determine the sulfonylurea herbicides in orange sample. Several factors affecting experiment result were investigated and the best extraction conditions were gotten. This method was successfully applied to determine four sulfonylurea herbicides in orange sample.2. Surfactant-enhanced USAEME-SFO coupled to HPLC-UV was developed to determine Strobilurins in orange juice sample. Several factors affecting experiment result were investigated and the best extraction conditions were gotten. This method was successfully applied to determine four strobilurins in orange juice sample.3. DSPE-USAEME coupled to HPLC-UV was developed to determine diethofencarb, pyrimethanil and azoxystrobin in orange juice sample. Several factors affecting experiment result were investigated and the best extraction conditions were gotten. This method was successfully applied to determine diethofencarb, pyrimethanil and azoxystrobin in orange juice sample.