Application Of Novel Despersive Liquid-Liquid Microextraction Methods In The Residue Analysis Of Strobilurins Pesticides

Strobilurins are a new class of fungicides which are efficient, low toxicity and broad-spectrum, they are widely used in agricultural production in order to control the powdery mildew and scab in fruits and vegetables. However, they can leave residues which must be controlled for food safety reasons. The European Commission have set the maximum residual limits (MRLs) of strobilurin fungicides in fruits, vegetables at a very low concentration, The high requirements on food quality have resulted in an increasing need for the reliable, sensitive and rapid analytical technique to monitor the fungicides at trace levels.Dispersive liquid-liquid microextraction (DLLME) is a novel environmentally benign sample-preparation technique, possessing obvious advantages of simple operation with a high enrichment factor, low cost, and low consumption of organic solvent, etc. So, DLLME is widely used to detect the trace and ultra-trace analytes in food, medicine, biological and environmental samples, In this paper, we developed three simple, sensitive, and viable methods respectively coupled to high performance liquid chromatography. for the determination of four strobilurin fungicides in water samples and fruit juice samples. The main work is as follows.1.Developing a dispersive liquid-liquid microextraction (DLLME) technology combined with high performance liquid chromatography (HPLC) was applied to detect four strobilurin fungicides in water samples. The effects of various experimental parameters, such as the kind and the amount of extraction solvent and disperser solvent, salt concentration, extraction time were optimized.Then the method was applied to analyze pesticide residues in water samples.2.Using temperature as assisted tool, developed temperature-assisted ionic liquid dispersive liquid-liquid microextraction (TAIL-DLLME) followed by HPLC-DAD was applied for the determination of four strobilurin fungicides (Picoxystrobin-. kresoxim-methyl、 pyraclostrobin、 trifloxystrobin) in aqueous samples and fruits samples. The effects of various experimental parameters, such as the type and the amount of ionic liquid (IL) and disperser solvent, time and temperature of heating,sample pH,salt concentration, time of extraction were investigated and optimized. The water samples and fruit juice samples were successfully analyzed using the proposed method.3.Ionic liquid-based ultrasound-assisted emulsification microextraction (IL-USAEME) was applied to extract strobilurin fungicides from fruit juice samples and strobilurin fungicides were determined by high performance liquid chromatography. In this work,1-octoyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]) and ammonium hexafluorophosphate was used as extraction solvent and ion-pairing agent separately. The effects of various experimental factors, such as the type and the volume of ionic liquid(IL),time and temperature of ultrasound, and the amount of NH4PF6were investigated and optimized. The fruit juice samples were successfully analyzed using the proposed method.