啶酰菌胺在草莓和土壤中的残留及消解动态

通过两年两地的田间试验,采用分散固相萃取-气相色谱-质谱联用的分析方法,研究了50%啶酰菌胺水分散粒剂在草莓和土壤中的残留及消解动态,并探讨了不同农作物品种、环境气候条件对农药消解速率的可能影响。结果表明:在草莓中添加0.05、0.3和3 mg/kg的啶酰菌胺标准品时,其平均回收率为91%~121%,相对标准偏差(RSD)为5.8%~9.9%;在土壤中分别添加0.1、0.3和3 mg/kg的啶酰菌胺时,其平均回收率为91%~100%,RSD为5.4%~6.5%。草莓和土壤中啶酰菌胺的定量限分别为0.05和0.1 mg/kg。啶酰菌胺在草莓中的消解动态符合准一级动力学方程,半衰期为6.2~11.8 d,但在山东和北京土壤中的消解试验均未拟合出指数方程。试验表明,50%啶酰菌胺水分散粒剂以有效成分337.5 g/hm2的推荐高剂量分别施药3次,采收安全间隔期为3 d时,啶酰菌胺在草莓和土壤中的最大残留量分别为1.97及0.38 mg/kg,最终残留量符合残留要求,可以安全使用。

Residue and dissipation dynamics of boscalid in strawberry and soil

Field experiments were conducted to study the residues and dissipation dynamics of boscalid in Chinese strawberry and soil in Shandong and Beijing for two years. The dispersive solid phase extraction combined with gas chromatography-mass spectrometry (GC-MS) method was established to determine the boscalid residue in strawberry and soil rapidly. The impact of different variety of agricultural products and environmental conditions on digestion rate were studied. The recoveries of boscalid in strawberry were 91%-121% with RSDs between 5.8% and 9.9% with spiking at 0.05, 0.3 and 3 mg/kg. The limit of quantitation (LOQ) of this method in strawberry samples was 0.05 mg/kg. The recoveries of boscalid in soil were 91%-100% with RSDs between 5.4% and 6.5% with spiking at 0.1, 0.3 and 3 mg/kg. The LOQ of this method in soil samples was 0.1 mg/kg, which could meet the requirement of max residue limits (MRLs) of boscalid. In decline study, the dissipation equations of boscalid in strawberry fit the pseudo-first-order reaction dynamic equations or the first-order reaction dynamic equations, and the half-lives of dissipation of boscalid were estimated to be 6.2 d and 11.8 d in strawberry. Boscalid was detected in soil samples from Shandong and Beijing, however, its dissipation dynamic equations did not fit the first-order reaction dynamic equation. The recommended dosage of 50% boscalid WG for control of grey mold in strawberry was 337.5 g/hm², the drug may delivered no more than 3 times, each time should over 3 d interval. The maximum final residue of boscalid strawberry and soil were 1.97 mg/kg and 0.38 mg/kg, respectively.