Abstract: This project is to compare the recovery determination of BHC and DDT with three different sample preparation methods: acetone-petroleum ether two step abstraction method, petroleum ether one step abstraction method and digestion method. The results showed: there’s no obvious difference among the three sample preparation methods at the concentration of 5ng/g (p>0.05). When the concentration is 50ng/g (p<0.05), the acetone-petroleum ether two step abstraction method and digestion method show great difference in comparison with petroleum ether one step abstraction method, while the recovery of the two previous methods is both higher than the one step method. But when the sample is of the concentration of 150ng/g (p<0.05). The recovery of digest method is obviously higher than other methods.

Key words:  , BHC； DDT； gas chromatography； sample preparation； recovery；