Abstract: This research establishes the high performance liquid-string of mass spectrometry determination of pretilachlor in the soil. Sample water extraction,purification by MCS hybrid cationic exchange SPE column,with 10.00 mL 3% of ammonia-methanol elution mixture,collect the eluent, using electrospray ion source（ESI⁺）,scan multiple reaction monitoring MRM mode,external standard method. The results show that the recovery was 90%~116%,relative standard deviation was 5.3%~12.5%,quantitative limit of 0.000 5 mg/kg. The method was simple,accurate and reliable,before treatment is suitable for the batch sample detection.

Key words: pretilachlor, soil, high performance liquid-string of mass spectrometry, residual quantity