Determination of Kresoxim-methyl Residues in Cucumber and Soil by Capillary Gas Chromatography

The residue analysis method of kresoxim-methyl and its dissipation rate in cucumber and soil were studied.Kresoxim-methyl were extracted from cucumber and soil matrices with acetone,purified by liquid-liquid extraction and Florisil cartridges,and then determined by GC with NP-detector.The limit of detection was estimated to be 9×10~-12 g,and the minimum determination concentration of kresoxim-methyl in cucumber and soil was 0.005 mg/kg and 0.010 mg/kg,respectively.The average recoveries ranged from 89.4% to 104.3% with a coefficient variation between 4.6% and 7.0%.The results showed that the half-lives of kresoxim-methyl in cucumber and soil were 6.4 days and10.3 days,respectively,at double of the recommended dosage300 g/hm~2.The present studyrevealed that the cucumber was sprayed at 3~4 times successivvely at the recommended dosages150 g/hm~2 and double of that,the residues in cucumber were below the MRL0.05 mg/kg,fixed by EU after 5 days for both treatments.