Study On Pretreatment Technology Of Tea Pesticide Residue Sample In Rapid Detection

In detection of pesticide residues, preparing the tested sample refers to exclude analytical interferents and extract pesticide residues as much as possible, which is very important in the rapid detection of pesticide residues and mainly includes the steps of sample preparation, extraction, purification, concentration etc., This paper established ultrasonic and microwave assisted extraction methods of pesticide residues combining with enzyme inhibition assay for rapid detection of pesticide residues, A comparative study of two kinds of sample pretreatment technology to screen out the best extraction method. The experiment selected ethyl acetate (lOmL) as the extraction solvent, respectively extract the organ ophosphorus pesticide residues in the tea under the ultrasonic and microwave.. The extraction of the sample lpassed through the purification column,of 0.2 g activated carbon with 1 g silica gel and elued with 10 mL of acetonitrile and 5 mL of benzene acetonitrile and then detected by rapid testing method with enzyme inhibition. Finally the experiment established the preparation technology which combines with Ultrasonic pretreatment method and Microwave pretreatment method, and shorten the testing time on the premise of guaranteed pesticide recovery in maximum extent.The main findings are as follows:1 Extraction solvent and adsorbent chose the same standard.The highest extraction and the lest impurities. Acetonitrile,Ethyl acetate,and Acetone was chosen as the extraction solvent.The results showed that the Ethyl acetate(10mL) extraction was the best.Florisil, Silica gel, Activated Carbon, Silica gel, activated carbon were used as adsorbents respectively.The results showed that purifying effect of Silicone 1g+Activated carbon 0.2g was best, both in the recoveries and the senses.Then,use 5 mL of benzene+10 mL of acetonitrile as the eluent.2 Using ultrasonic extraction and microwave assisted extraction as the pretreatment technology of experiments, the extraction conditions were optimized.In experiment, the ultrasonic extraction time was optimized.The results showed 10min was the best and the residues were extracted with ultrasound again for 5min.While,in the experiment of microwave assisted extraction of pesticide residues,,using orthogonal experiment method to optimize the microwave extraction time and temperature. The results showed that the best recoveries at 70 ℃ wae 8min. Using chlorpyrifos as an example, the average recovery rate was 88.80%-99.90%.3 The combination of ultrasonic assisted extraction and microwave extraction method used in extraction of pesticide residue in the sample. The optimization of extraction conditions by orthogonal experiment, of the recovery of four organic phosphorus pesticides, the rate of speed, solvent dosage etc showed that best extraction conditions were:60 ℃ in microwave extraction for 8min and then the ultrasonic extraction for 5min, and the recovery rate of the combination of two methods increased, compared with the use of a single extraction method. The recovery rates were between 78.64%-100.80%.