丁醚脲在柑橘及其土壤中的残留及消解动态

建立了丁醚脲在柑橘及橘园土壤中残留测定的超高效液相色谱-串联质谱（UPLC-MS/MS）检测方法，研究了其在柑橘和土壤中的消解动态及最终残留。样品采用乙腈提取，N-丙基乙二胺（PSA）净化，UPLC-MS/MS 检测。结果表明:在0.01、0.1和1 mg/kg 3个添加水平下，丁醚脲在柑橘全果、果肉和果皮中的回收率在84% ~89%之间，相对标准偏差（RSD）为2.6% ~7.2%，在土壤中的回收率为83% ~86%，RSD为2.2% ~5.6%；在广东、广西和福建3地柑橘及土壤中，其消解半衰期分别为3.7 ~4.4 d和4.1~5.4 d，表明丁醚脲消解较快；采用 500 g/L丁醚脲悬浮剂（SC），分别按有效成分500和750 mg/L 的剂量于幼果期开始施药，施药2~3次，施药间隔期为10 ~14 d，距最后一次施药后21 d采样测定，柑橘果肉中丁醚脲的残留量均<0.01 mg/kg ，全果中的最终残留量均低于我国制定的丁醚脲在柑橘中的最大允许残留限量（MRL）标准（0.2 mg/kg）。

Residues and decline study of diafenthiuron in orange and soil

A ultra high performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS) method was developed for determining diafenthiuron residues in orange and soil.The dissipation curve and final residues of diafenthiuron at PHIs were studied.The samples were extracted with acetonitrile,cleaned with N-propylethylenediamine(PSA) and detected with UPLC-MS/MS.The fortified recoveries ranged from 84% to 89% with relative standard deviations of 2.6% to 7.2% in whole fruit,flesh and peel,from 83% to 86% with relative standard deviations of 2.2% to 5.6% in soil when diafenthiuron was spiked at 0.01,0.1 and 1 mg/kg levels.The results of residue dynamics indicated that the half-lives of diafenthiuron in orange and soil were 3.7-4.4 d and 4.1-5.4 d,respectively.The orange was sprayed with 500 g/L SC at dosage 500-750 mg/L(2-3 times) at young fruit period,the interval period was 10-14 days,the final residues of diafenthiuron were all below the 0.01 mg/kg in flesh at the 21st day after last application.The residue of whole fruit was below the maximum residue limit(MRL) set by China(0.2 mg/kg).