Abstract:Polar organophosphorus pesticides, such as dimethoate, dichlorvos, phorate and methyl parathion, have similar polarity with water. Meanwhile, their content in groundwater is relatively low. However, it is difficult to extract polar organophosphorus pesticides from water when using methylene chloride as solvent, which has low extractive recoveries, poor stability and high detection limit. Through the addition of acetone as an auxiliary extractive solvent, the recoveries and stability were significantly improved. In this method, acetone-dichloromethane(1∶9, v: v)was used as the extracting solvent, which detected dichlorvos, phorate, dimethoate, methyl parathion, chlorpyrifos and parathion in the groundwater through liquid-liquid extraction and gas chromatography-flame photometric detector. Under the optimized conditions, the average recovery rate of water samples was in the range of 88. 1%~109%, with RSDs(n=3)between 0. 28% and 4. 27%. The detection limit was 1. 17~4. 22 ng/L. The modified analysis method significantly improved the validity parameter, such as accuracy and precision, which is beneficial for more accurate analysis of polar organophosphorus pesticides in groundwater.