氟啶虫胺腈在棉花和土壤中的检测方法与残留动态研究

研究和建立了氟啶虫胺腈在土壤、棉籽和棉叶中的高效液相色谱检测方法,并在天津和杭州两地开展了氟啶虫胺腈在棉花中的田间残留试验研究。样品采用乙腈提取,正己烷萃取,氟罗里硅土柱层析净化,正己烷/丙酮(体积比6∶4)混合液洗脱,减压浓缩至干,甲醇定容,高效液相色谱配可变波长紫外检测器进行检测。当分别在空白土壤、棉籽和棉叶样品中添加浓度为0.05~2.5mg·kg-1的氟啶虫胺腈标准品时,其平均添加回收率在76.81%~94.43%之间,相对标准偏差(RSD)在0.54%~7.20%之间;氟啶虫胺腈的最小检出量为1 ng,在所有样品中的最低检出浓度均为0.05mg·kg-1。田间残留试验结果表明,氟啶虫胺腈在土壤和棉叶中的消解规律符合一级动力学模型Ct=C0e-kt,消解半衰期分别为1.36~5.10 d和6.13~9.37d。最终残留试验结果表明,在棉花田手动喷雾施用50%氟啶虫胺腈水分散粒剂,按推荐剂量和1.5倍推荐剂量施药,兑水喷雾处理2~3次,每次施药间隔7 d,在距最后1次施药7、14 d和21d时,氟啶虫胺腈在棉籽和土壤中的残留量均小于方法最低检出浓度0.05mg·kg-1。

Residue Determination and Degradation of Sulfoxaflor in Cotton and Soil

An analytical method with high performance liquid chromatography (HPLC) was established for determining sulfoxaflor residue in soil, cotton seeds and cotton leaves. The field residue decline study and final residue trials of sulfoxaflor in cotton in Tianjin City and Hangzhou City, were designed. The samples were extracted with acetonitrile, partitioned by n-hexane, purified using Florisil column, and determined by HPLC equipped with a variable wavelength detector (VWD). The results showed that when the spiked levels were 0.05 mg·kg-1to2.5 mg·kg-1, the average recovery of sulfoxaflor ranged from 76.81% to 94.43% with relative standard deviation (RSD) of 0.54% to 7.20%;the limit of detection(LOD)of sulfoxaflor was 1 ng, and the limit of quantification (LOQ) was 0.05 mg·kg-1in soil, cotton seeds and cotton leaves. The degradation of sulfoxaflor in soil and cotton leaves could be described with an equation: Ct=C0e-kt. The half-life of sulfoxaflor were1.36~5.10 d and 6.13~9.37 d in soil and cotton leaves, respectively. The wheat was sprayed with 50% water dispersible granule (WDG) at dosage0.6~0.9 g·30 m-2 (2~3times) atfull-bloomstage,theintervalperiodwas7 d,the final residues ofsulfoxaflorwere lowerthan LOQ insoil and cotton seeds.