Abstract: To establish disperse liquid-liquid microextraction coupled with liquid chromatography-mass spectrometry（DLLME-LC-MS） method for determination of eight organophosphorus pesticides（dimethoate,dichlorvos,malathion,parathion,phorate,diazinon,ethion,chlorpyriphos） in Codonopsis radix. The eight organophosphorus pesticides in Codonopsis radix which was extracted by trichlormethane,and the acetonitrile was dispersant,then analysed by using mass spectrometric ditection in multiple reaction monitoring（MRM） mode under the optimal chromatographic conditions. The external standard method was adopted for quantitative analysis. The eight organophosphorus pesticides have a good linear relation respectively（r﹥0.999 0）. The recoveries at three spiked levels of eight organophosphorus pesticides ranged from 76.81% to 110.25%,the detection limits were 0.006~1.300 μg/kg. The method can be applied in detection of the organophosphorus pesticides residues analysis in Codonopsis radix.

Key words: Codonopsis radix, organophosphorus pesticides, disperse liquid-liquid microextraction, LC-MS