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目的研究螺螨酯通过喷雾施药方式在苹果和土壤中的残留水平及消解动态,制定螺螨酯悬浮剂防治苹果叶螨的安全间隔期。方法在北京、安徽及山东3地进行农药残留的田间消解试验。样品采用乙腈提取,经弗罗里硅土固相萃取柱净化,气相色谱-电子捕获检测器(gas chromatography-election capture detector,GC-ECD)检测,外标法定量。结果在添加水平为0.01~2 mg/kg范围内,螺螨酯在苹果及土壤中的添加回收率为91.6%~104.6%,相对标准偏差为1.4%~4.2%;方法定量限为0.01 mg/kg。在北京、安徽及山东3地试验中,螺螨酯在苹果及土壤中的消解动态符合一级动力学指数模型,在苹果中的半衰期为11~19 d,在土壤中的半衰期为1.4~4.1 d。按照推荐高剂量及其1.5倍剂量施药1次和2次,在距末次施药间隔为30、40、50 d苹果样品中,螺螨酯的残留量均低于0.071 mg/kg。结论参照国际食品法典、美国及欧盟规定的螺螨酯在苹果上的农药最高残留限量均为0.8 mg/kg,在推荐施药条件下,采收间隔30 d之后的苹果是安全的。
OBJECTIVE To study the residual levels of spirodiclofen in spraying apples and soil and the dynamic state of digestion, and to establish the safety interval of Spirodiclofen Suspension to control spider mites in apple. Methods Pesticide residue digestion experiments were conducted in Beijing, Anhui and Shandong. Samples were extracted with acetonitrile, purified by Florisil SPE, GC-ECD and quantified by external standard method. Results The recoveries of spirodiclofen in apple and soil ranged from 91.6% to 104.6% and the relative standard deviations (RSDs) ranged from 1.4% to 4.2% at the spiked levels of 0.01-2 mg / kg. The limit of quantification was 0.01 mg / kg. In Beijing, Anhui and Shandong, the digestive activity of spirodiclofen in apple and soil conformed to the first-order kinetic index model, the half-life in apple was 11-19 days, and the half-life in soil was 1.4-4.1 d. In accordance with the recommended high dose and its 1.5 times the dose of 1 and 2 times, from the last application interval of 30,40,50 d apple samples, spirodiclofol residues were less than 0.071 mg / kg. Conclusion According to the Codex Alimentarius, the maximum residue limit of pesticides for spirodiclofen in American and European Union is 0.8 mg / kg. Apples collected at intervals of 30 d are safe under the recommended application conditions.