八氯二丙醚在不同茶树品种上的残留消解研究

Residue and Degration Dynamics of bis-(2,3,3,3-tetrachloropropyl)Ether on Tea Leaves

采用气相色谱(GC-ECD)分析方法,研究了八氯二丙醚(S421)在碧香早、槠叶齐、群体品种等3种不同茶树上的消解动态和最终残留。茶叶样品用水-丙酮-正己烷(2∶2∶3,V/V)提取,离心后合并提取液在40℃水浴中吹至近干,加入1 mL正己烷,浓硫酸磺化后取上清液供GC-ECD检测,外标法定量。结果表明,S421在碧香早、槠叶齐、群体品种上的半衰期分别为5.18 d,4.44 d和3.83 d。在茶叶上施用S4216 000倍液3次,距末次施药后30 d采样测定春秋两季茶叶中S421的残留量低于欧盟制订的S421在茶叶中的MRL值0.01 mg·kg-1。茶叶品种、生长期、采摘期和气温可能影响S421在茶叶上的消解。

GC-ECD method was used for determining the final residue and degradation dynamic of S421 in the tea leaves of Bixiangzao,Zhuyeqi and other population variety. S421 was extracted from tea samples using water-hexane-acetone （2：2：3,V/ V）,and then centrifuged. The combined organic layer was evaporated to dryness. Results showed that the degradation equations of S421 accorded with the first-order kinetics equation in tea leaves,and their half-life of degradation were 5.18 d, 4.44 d and 3.83 d. 30 days after S421 at dose of 6 000 times on tea trees three times,final residue was lower than 0.01 mg· kg^-1. Tea cultivars,growth stage,picking period, and temperature affected residual dynamics of S421 in tea leaves.