25%多效唑悬浮剂在小麦上的残留动态研究

应用气相色谱检测技术研究了25%多效唑悬浮剂在小麦土壤、小麦植株和籽粒中的残留分析方法和降解规律。采用田间试验方法,小麦拔节期施用450mL/hm2和900mL/hm2的多效唑,样品用丙酮和水提取,二氯甲烷液液分配,中性氧化铝层析柱净化。最低检测浓度为0.02mg/kg,添加浓度水平为0.1mg/kg、0.5mg/kg、2.0mg/kg时,在土壤、植株和籽粒中的回收率分别为92.0%～101.0%、89.0%～101.0%和85.2%～93.4%,变异系数分别为1.95%～3.16%,2.05%～3.94%,2.58%～3.67%。结果表明,多效唑在小麦土壤和植株中的降解规律均符合一级动力学方程C=Coe-kt。多效唑在吉林、黑龙江、山东省三地小麦土壤和植株中的降解半衰期分别为0.8d～6.9d和0.3d～1.8d,收获期小麦土壤、植株和籽粒的最终残留量均低于各自的检测极限,建议25%多效唑悬浮剂的用量不要超过450mL/hm2。

Residual Dynamics of Paclobutrazol 25% Suspension Concentrate on Wheat

The degradation rules and residual of paclobutrazol 25% SC in wheat field were studied by using GC. In field trial, the paclobutrazol at the dosage of 450 mL/hm2 and 900 mL/hm2 was used on the wheat in its jointing stage. The samples were extracted with a mixture of acetone and water, followed by liquit-liquit partition with dichloromethane, and cleaned up by a column of neutral A1203. The LOQ was 0.02 mg/kg. At different addition level of 0.1, 0.5, 2.0 mg/kg, the wheat seed were 90.0%-101.0%, 89.0%-101.0% and 85.2%-93,4%, respectively. The CV were 1.95%-3.16%, 2.05%-3.94% and 2.58%-3.67%, respectively. The results indicated that degradation of paclobutrazol in soil and plant samples were accordance with the first-order kinetic equation C=Coe-kt. The half-lives ofpaclobutrazol in soil and in plant were 0.8 d-6.9 d and 0.3 d-1.8 d in Jilin, Heilongjiang and Shandong. The terminal residues in siol, wheat plant and seed were less than the detectable limits. It was suggested that the dosage of 25% Daclobutrazol SC was 450 mL/hm2 at most.