Application Of New Sample Pretreatment Technique In The Residue Analysis Of Strobilurins Pesticides

Pesticide is extensively applied in agriculture production. It Made a great contribution for protecting crops and increasing crop yields. As a kind of important fungicide with high efficiency and broad spectrum, strobilurin fungicide are widely used for their excellent fungicidal activity to almost all fungal diseases. They are often used to prevent and control the gibberellic disease, powdery mildew and early blight in cereals, fruits and vegetables owing to their high selectivity, strong fungicidal activity and low dosage rate.Due to the good osmosis and systemic action of strobilurin fungicide, they can be absorbed by plant and caused residue in plant body. It not only brings a threat to the edible safety of crops, but also has negative impacts to the environment. On the other hand, the component content of this kind of fungicide in actual sample is lower, so a higher requirement is proposed for the the sensitivity and detection limit of the instruments and methods. Therefore, it is necessary to establish some accurate, rapid and simple sample preparation methods to purify and enrich aimed fungicides from actual sample for the residue detecting.Solid phase extraction technique (SPE) is a simple and convenient pretreatment sample technology based on the solid-liquid separation extraction, which has low organic solvents consumption, simple target components collection, good purification effect,high enrichment factor and the easiness to realize automation.Dispersed micro solid phase extraction technology (D-μ-SPE) is a emerging technology developed from solid phase extraction technology. The adsorbent disperses in the sample solution directly, without the use of solid phase extraction column, the operation is simpler and faster. Hollow fiber membrane liquid micro extraction technology (HF-LPME) is a simple and low cost technology with only a few organic solvent for extraction, meanwhile due to the application of hollow fiber membrane, the solvent loss is avoided,the extraction efficiency is increased and the matrix interference is reduced.It is a high efficient and environmental friendly liquid micro extraction method.In the SPE and D-μ-SPE technology,the recovery ratio and enrichment factor can be effectively enhanced by choosing appropriate adsorption material. Therefore, research and development of high performance new adsorbent has become one of the research hotspots in this sample pretreatment technology. Graphene is a new nano material solely composed of carbon atoms with a single flake structure. It has outstanding conductivity and high mechanical strength.In addition, the huge specific surface area of graphene makes it have a excellent adsorption property and great adsorption capacity to numerous atoms and molecules.Thus it is a kind of novel adsorption material with lots of potential.In this paper, graphene was used as the adsorbent of SPE and D-μ-SPE technology and the two technology were applied in water sample and orange sample for the residues analysis of strobilurin fungicides. The HF-LPME technique was applied in water and fruit juice sample.The experimental conditions were optimized, and the main research contents are as follows:1.With the use of graphene as adsorbent,the SPE technology combined with high performance liquid spectrometry (HPLC) was applied to detect three strobilurin fungicides in water sample. The extraction conditions such as adsorbent,eluent, eluent volume, sample volume were optimized and the method was successfully applied in water sample analysis.2.With the use of graphene as adsorbent,The D-μ-SPE and HPLC were combined for the detection of four strobilurin fungicides in water sample and orange sample. The related conditions including adsorbent quality, extractant, graphene mass, ultrasonic time, vortex time, pH were optimized and the method was used in water and orange sample analysis.3.The HF-LPME combined with HPLC was used to determine three strobilurin fungicides in water and juice sample.The influential conditions such as extractant, stirring speed, stirring time, extraction temperature, pH and ionic strength were optimized and the method was applied for fungicides residues analysis in water and juice sample with success.