Determination of pesticide residues in vegetables in the current market
March 14 08:35:10, 2019
At present, pesticides used in production can be roughly classified into organochlorines, organic phosphorus, and carbamates. Pyrethroid pesticides are synthetic insecticides that simulate the active molecular structure of pyrethrum plants. They have contact toxicity and stomach toxicity. They are moderately toxic to humans and animals, and are low in toxicity but have low residual toxicity. In China, cypermethrin, deltamethrin, fenvalerate and Other pyrethroid pesticides and chlorothalonil are listed as the pesticides that can be used in the production of Class A green food, and there are clear regulations on the safety intervals and residues. 1. Material Methods So far, there is a lack of background information on the residual amount of pyrethroid pesticides in vegetables. After China's accession to the WTO, in order to provide the necessary conditions for export earnings, it is more urgent to grasp the amount of various pesticide residues contained in vegetables. We used representative vegetables produced in the Xiongyuecheng area of ​​Yingkou Economic Development Zone as materials, and determined the content of pyrethroid pesticides contained in them. The tested vegetables include spinach, Chinese cabbage, and cucumber; the reagents used are superior pure reagents produced by Shenyang Chemical Reagent Factory. The spinach, pakchoi, and cucumber were chopped and placed in a mortar and pestle to purify and purify, and each sample was subjected to 3 replicate tests. The standard samples of cypermethrin, fenvalerate and deltamethrin pesticides used were standard chromatographic reagents prepared by Sinopharm Chemical Reagent Co., Ltd. 2. Analysis of Results In this experiment, gas chromatography was used to determine the recoveries of deltamethrin, cypermethrin, fenvalerate, and chlorothalonil in cucumber, pakchoi, and spinach. The results showed that the recovery rate of various pesticides in the above vegetables was in the range of 79.30% to 115.80%, which complied with the national allowable standard of 70% to 120%. The standard deviation is in the range of 3.25% to 13.21%, which is within the allowable range error. At the lowest detected concentration, the detection limit of the detector for pyrethroid pesticides was 0.02 micrograms per kilogram. The test results show that the above pesticides in Chinese cabbage are all less than the limit indicators. However, the residual amount of cypermethrin in spinach was 1.0 mg/kg higher than the limit value; the fenvalerate residue in cucumber was 0.5 mg/kg higher than the limit value. The reason for the excess of cypermethrin residues in spinach may be due to the fact that cypermethrin has a long shelf life, is stable to light, is not easily degraded, and takes a long time to remain in vegetables, or it is a vegetable growing household that violates the requirement of not using pesticides 15 days before harvest. In order to obtain a good-looking product, cucumbers are used in a large amount of greenhouse cultivation. Cucumber and spinach are currently considered as one of the vegetables with the most pesticide residues, and this is also demonstrated in the tests. The results showed that the residues of deltamethrin, cypermethrin and chlorothalonil in cucumber were lower than the limit, but the fenvalerate residues were higher than the limit; the pesticide residues in Chinese cabbage were all lower than the limit; the deltamethrin in spinach The residues of fenvalerate and chlorothalonil were all lower than the limit, but the cypermethrin residue was higher than the limit. The recoveries of the above pesticides ranged from 79.30% to 115.80%, which complied with the national permitted standards. 3. Suggestions In order to realize the pollution-free production of agricultural products and meet the quality standards, on the one hand, training on the cultivation techniques for non-environmental pollution of farm households should be strengthened, and good agricultural standards should be actively promoted to ensure the quality and safety of good products from the source. On the other hand, we should carry out the analysis of damages and key systems for crop products, livestock products, and aquatic products, and ensure the quality of agricultural products from the source. Starting from the two areas of origin and market, the whole process of agricultural products from the farmland to the table shall be subject to quality and safety control. Pyrethroid pesticides and trichlorfon residues (mg/kg) in vegetables