嘧菌酯在荔枝上的消解动态及最终残留的研究

建立嘧菌酯在荔枝上的残留分析方法，并于2011-2012年在广州和南宁进行250 g · L -1嘧菌酯悬浮剂在荔枝上的田间试验，研究其在荔枝上的消解动态和最终残留。采用甲醇提取，弗罗里硅土和中性氧化铝柱层析净化，气相色谱法（ECD）检测嘧菌酯残留量。在添加水平为0.01、0.1和1 mg · kg -1时，荔枝果肉、全果和果皮中平均添加回收率分别为83.0％～85.1％、83.3％～84.9％和80.6％～84.5％；相对标准偏差分别为2.24％～3.88％、2.77％～3.84％和2.90％～3.68％；检出限（LOD）为0.005 mg · kg -1；定量限（LOQ）为0.01mg·kg -1。田间试验结果表明，嘧菌酯在广州和南宁荔枝中的半衰期分别为2.8～5.7d和3.5～7.2d，消解迅速。250 g · L -1嘧菌酯悬浮剂，200 mg · kg -1施用3～4次，于末次施药后7 d ，荔枝全果上残留量为0.01～0.16 mg · kg -1，果肉中残留量均小于0.01 mg · kg -1，果皮中残留量为0.02～0.73 mg · kg -1；于末次施药后14 d ，全果残留量为＜0.01～0.12 mg · kg -1，果肉中的残留量均小于0.01 mg · kg -1，果皮中的残留量为0.01～0.54 mg · kg -1，全果中的最终残留量低于我国规定的M RL值0.5（mg · kg -1）。

Dissipation and Terminal Residue of Azoxystrobin in Lychee Under Field Conditions

We developed an effective method to determine the azoxystrobin residue in lychee And field trials were designed to evaluate the dissipation and residue of azoxystrobin in lychee at Guangzhou and Nanning .The samples were extracted by methanol and detected by GC-ECD .The results showed that the average recoveries of 83.0% -85.1% ,83.3% -84.9% and 80.6% ~ 84.5% with relative standard deviations of 2.24% -3.88% ,2.77% -3.84% and 2.90% -3.68% at the spiked level of 0.01 ,0.01 and 1 mg · kg -1 .The limit of detection （LOD） was 0.005 mg · kg -1 and the limit of quantification （LOQ ） was 0.01 mg · kg -1 . Meanwhile , the half lives of azoxystrobin in lychee of Guangzhou and Nanning were 2.8 -5.7 days and 3.5 -7.2 days ,respectively ,and the terminal residue were 0.01-0.16 mg · kg -1 ,〈0.01mg · kg -1 and 0.02-0.73 mg · kg -1 in the whole fruit ,flesh and peel at the 7days after last application ,and were 〈0.01-0.12 mg · kg -1 ,〈0.01 mg · kg -1 and 0.01-0.54 mg · kg -1 in the whole fruit ,flesh and peel at the 14 days after last application .Our results suggest that the terminal residue in whole fruit are all below the maximum residue limit （MRL） set by China （0.5 mg · kg -1 ） .