气相色谱法检测茶叶对点燃蚊香中八氯二丙醚的吸附作用

Detection of octachlorodipropyl ether residue in tea adsorbed from the combustion of the mosquito coils by gas chromatography

建立了用毛细管柱气相色谱法测定茶叶中八氯二丙醚（S-421）残留量的方法,用该方法检测茶叶对点燃蚊香中八氯二丙醚的吸附作用。茶叶样品用正己烷提取,经硅藻土545-浓硫酸（1g-0.4mL）净化,以正己烷洗脱。经毛细管气相色谱柱DB-1701（30m×0.32mm×0.25μm）分离,电子捕获检测器测定,外标法定量。S-421在0.010-0.200mg/L浓度范围内线性关系良好（r=0.9992）;添标水平为0.04、0.10mg/kg和0.16mg/kg时,平均回收率在92.4%-96.9%之间,相对标准偏差小于4.0%;方法的定量限为0.01mg/kg。该法操作简单,实验结果准确可靠;用该方法检测到茶叶能直接吸附点燃蚊香中的八氯二丙醚,蚊香中的八氯二丙醚是构成茶叶中八氯二丙醚残留的主要来源之一。

A gas chromatographic method was developed for the determination of octachlorodipropyl ether（S421） residue in tea.The proposed method was used to study the adsorption effect on S-421 from the combustion of the mosquito coils by tea.S-421 was extracted from tea samples using n-hexane,purified with celite 545-sulfudc acid（1 g-0.4 mL） using hexane as an eluent,and then analyzed by gas chromatography using DB-1701 capillary column（30 m×0.32 mm×0.25 μm） for separation and electron capture detector（ECD） for detection.The method of external standards was used in determination.A good linear correlation for S-421 was obtained over the range of 0.010~0.200 mg/L（r=0.9992）.Average recoveries of S-421 from tea spiked at three concentration levels of 0.04,0.10 mg/kg and 0.16 mg/kg ranged from 92.4% to 96.9% with relative standard deviation less than 4.0%.The limit of quantitation（LOQ） was 0.01 mg/kg.The proposed method was easily operative and accurate for precise determination of S-421 residue in green tea with satisfactory results.It was found that one of the main sources of S-421 in tea may be the adsorption from the combustion of the mosquito coils.