Determination of Kresoxim-methyl Residues in Cucumber and Soil by Capillary Gas Chromatography CHEN Chang-long, LI Jian-zhong, WU Xian, HU Ji-ye *
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Abstract
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 and 10.3 days,respectively,at double of the recommended dosage (300 g/hm2).The present study revealed that the cucumber was sprayed at 3~4 times successivvely at the recommended dosages (150 g/hm2) and double of that,the residues in cucumber were below the MRL (0.05 mg/kg,fixed by EU) after 5 days for both treatments.
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