Chlopyrifos residues in soils were determined by gas chromatography. The average recovery rates were 90.2%, 95.0%and 94.0 in 1, 10 and 100mg/kg chlopyrifos respectively. And their variation coefficients were between 2.5 and 3.3%. The average recovery rates were 87.8%, 90.3% and 91.6% in 0.1, 1.0 and 10mg/kg methamidophos respectively. And their variation coefficients were between 3.1 and 4.2%. The average recovery rates were between 91.7% and 99.2% in different concentrations of chlopyrifos and methamidopho...