茶叶中八氯二丙醚(S-421)的检测及污染来源研究

建立了茶叶中八氯二丙醚(S-421)残留的检测方法,并明确了茶叶中八氯二丙醚的污染来源。茶叶样品用正己烷-丙酮(22∶ 3,V/V) 提取,经硅藻土545-浓硫酸(1 g+0.4 mL)净化,以正己烷洗脱,GC-ECD检测,外标法定量。在0.01~1.0 mg/kg的添加水平下,平均回收率在93.0%~96.6%之间,相对标准偏差在1.70%~4.05%之间,方法的定量限为0.01 mg/kg。该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求。用该方法对茶园常用化学农药25种、生物源农药11种、肥料9种、叶面肥7种进行检测,均未检测到八氯二丙醚残留,但茶叶能直接吸附蚊香、气雾杀虫剂中的八氯二丙醚。根据目前的研究结果认为,蚊香和气雾杀虫剂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。

Identification of the Sources and Gas Chromatographic Determination of Octachlorodipropyl Ether in Tea

A detection method of octachlorodipropyl ether(S-421) in tea using gas chromatograph with electron capture detector was reported. Octachlorodipropyl ether was extracted from tea samples using n-hexane-acetone(22∶ 3,V/V),purified with celite 545- sulfuric acid (1g-0.4mL) using hexane as an eluent. At the spiking level of 0.01 ~1.0 mg/kg,the recovery of this method was in the range from 93.0% to 96.6% with standard deviation of 1.70~4.05%,and the LOQ was 0.010 mg/kg. To identify the sources of octachlorodipropyl ether in tea that are commonly used for tea trees were examined,including 25 chemical pesticides,11 biological pesticides,9 fertilizers and 7 leaf fertilizers. No residues were found in the above material.It was found that the main sources of octachlorodipropyl ether in tea may be the absorption from the combustion of the mosquito coils and the aerosols.