气相色谱-质谱法测定茶叶中的25种有机氯农药残留

利用气相色谱-质谱(GC-MS)联用技术建立了茶叶中25种有机氯农药残留同时测定的方法。茶叶样品中有机氯农药残留通过正己烷-丙酮(体积比为2∶1)溶液提取,浓缩后过弗罗里硅土柱净化,采用正己烷-乙酸乙酯(体积比为9∶1)溶液淋洗,GC-MS选择离子监测模式(SIM)检测。方法的线性范围为0.010～0.500 mg/L。在茶叶样品中0.01～0.20 mg/kg加标水平下有机氯混标的加标回收率为70.8%～105.5%,相对标准偏差为1.6%～12.7%。除硫丹Ⅰ和硫丹Ⅱ的定量限为0.02 mg/kg以外,其余23种有机氯农药的定量限均为0.01 mg/kg。

Determination of 25 Organochlorine Pesticides in Tea by Gas Chromatography-Mass Spectrometry

A high performance gas chromatography-mass spectrometry (GC-MS) method for the determination of 25 organochlorine pesticides in tea has been developed. The samples of tea were extracted with n-hexane-acetone (2: 1, v/v). The extract was purified by using a Florisil column with n-hexane-ethyl acetate (9: 1, v/v) as elution solvent. Chromatographic analysis was performed on a DB-35MS capillary column. Satisfactory separation and sensitivity of 25 organochlorine pesticides were obtained with the proposed method. The analytical results show the working curves for 25 organochlorine pesticides were linear in the range of 0.010 - 0.500 mg/L by GC-MS on selective ion monitoring mode. The recoveries of 25 organochlorine pesticides at spiked levels of 0.01 -0.20 mg/kg were 70.8% - 105.5%, and relative standard deviations (RSDs) were 1.6% - 12.7%. The limits of quantitation were 0.01 mg/kg except that for endosulfan I and endosulfan II that were 0.02 mg/kg.