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目的建立高效液相色谱法检测甘蓝和土壤中丁醚脲的含量,并研究其在甘蓝和土壤中的代谢残留。方法样品经乙腈高速匀浆提取,土壤采取振荡提取,旋转蒸发,浓缩,用乙腈定容,通过滤膜过滤,经色谱柱分离。结果甘蓝、土壤中烯啶虫胺的最低检出浓度(limit of quantification,LOQ)均为0.01 mg/kg;在0.02~100μg/m L范围内丁醚脲的线性关系良好,R=1.0。甘蓝和土壤样品回收率在75.3%~102.3%,相对标准偏差(relative standard deviation,RSD)为3.7%~11.4%。代谢试验结果表明:2010年、2011年,河北、山东、河南3地丁醚脲在甘蓝中的消解半衰期为1.2~2.8 d,在土壤中的半衰期为1.8~4.4 d;最终残留实验结果显示,丁醚脲在甘蓝和土壤中的最终残留量均未检出,远低于最大残留限量(maximum residue limit,MRL)。结论在自然条件下,丁醚脲属于易降解农药,在推荐使用剂量下,对收获后的甘蓝相对安全。
OBJECTIVE To establish a HPLC method for the determination of diafenthiuron in cabbage and soil and to study the metabolic residues in cabbage and soil. Methods The samples were extracted by high speed homogenization with acetonitrile. The soil was extracted by shaking, rotary evaporated, concentrated and fixed with acetonitrile, filtered through a membrane filter and separated by column. Results The limit of quantification (LOQ) of nitenpyram in cabbage and soil were both 0.01 mg / kg. But the linear relationship of diafenthiuron was good in the range of 0.02 ~ 100 μg / mL with R = 1.0. The recovery rates of cabbage and soil samples ranged from 75.3% to 102.3%, and the relative standard deviations (RSDs) ranged from 3.7% to 11.4%. The metabolic test results showed that the diuretic half-lives of diafenthiuron in cabbage were 1.2-2.8 days in 2010 and 2011 in Hebei province, Shandong province and Henan province, respectively, and the half-lives in the soil ranged from 1.8-4.4 days. In the final residue experiment, The final residues of diafenthiuron in cabbage and soil were not detected, well below the maximum residue limit (MRL). Conclusion Under the natural conditions, diafenthiuron is an easily biodegradable pesticide, which is relatively safe to the cabbage after harvest at the recommended dosage.