气相色谱法测定石斛中的农药残留

建立了毛细管柱气相色谱法同时测定石斛中18种有机氯和拟除虫菊酯类农药残留的方法。石斛鲜条经匀浆，乙腈提取、净化后，选用HP-5毛细管色谱柱，通过柱程序升温，进行检测，外标法定量。结果显示：18种农药取得很好的分离效果，农药残留量在0．008～0．4Ixg／mL范围内方法的线性良好，相关系数为0．9961-0．9999，18种混合农药加标量为0．05mg／kg和0．5mg／kg时，加标回收率在75．3％-109．2％之间，相对标准偏差小于10％，检出限0．001-0．01mg／kg。

Determination of Pesticide Residues in Dendrobium Devoninum Paxt. by Gas Chromatography

Objective：To establish the capillary column gas chromatography method for the simultane- ous determination of eighteen residual organochlorine and pyrethroid pesticides in Dendrobium devoninum paxt.. Methods：Crushed samples were extracted from solvent, isolated and purified with SPE, separated by HP- 5 column with the column temperature program and analyzed by GC/ECD, quantitated by external standard method. Results：eighteen pesticides were separated from each other, The standard cure showed good linearity over the concentration range of 0.008 - 0. 4μ g/mL（ r：0.9961 - 0.9999）, the recoveries of pesti- cides at spiked levels of 0.05 - 0.5 mg/kg were 75.3 - 109.2%, the detection limits were in the range of 0.001 -0.01 mg/kg,the RSDs were less than 10%. Conclusion：The method is simple and accurate,It meets the determination demands of pesticides residues for Dendrobium devoninum paxt..