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Dissipation and residue fate of kresoxim-methyl in tobacco leaves and soil under field conditions

Author:
Nie, Yanhua, Zhang, Kankan, Chen, Hongyu, Zhang, Wen, Zhu, Huijun, Hu, Deyu
Source:
International journal of environmental analytical chemistry 2015 v.95 no.14 pp. 1338-1352
ISSN:
1029-0397
Subject:
detection limit, ecosystems, field experimentation, gas chromatography, half life, kresoxim-methyl, leaves, petroleum, soil, tobacco, China
Abstract:
The fate of kresoxim-methyl was studied in a tobacco field ecosystem, and a simple and reliable method was developed for the determination of kresoxim-methyl in soil, green and cured tobacco leaves. Kresoxim-methyl residues were extracted from samples with petroleum ether, and determined by gas chromatography (GC) coupled with an electron capture detector (ECD). Kresoxim-methyl (30% suspension concentration) was applied at 150 g a.i. ha –¹ (the recommended high dosage) and 225 g a.i. ha –¹ (1.5 times the recommended high dosage) in the experimental fields in Huishui and Changsha in China. The limits of detection (LODs) and limits of quantification (LOQs) of kresoxim-methyl in green tobacco leaves, cured tobacco leaves and soil were 0.012 and 0.04 mg kg –¹, 0.12 and 0.4 mg kg –¹, and 0.0015 and 0.005 mg kg –¹, respectively. The average recoveries were 84.5% to 95.7%, 79.8% to 94.3% and 83.3% to 93.8% with relative standard deviations (RSDs) less than 10% in green tobacco leaves at four spiked levels (0.04, 0.2, 2 and 8 mg kg –¹), cured tobacco leaves at three spiked levels (0.4, 1 and 10 mg kg –¹) and soil at three spiked levels (0.005, 0.05 and 0.5 mg kg –¹), respectively. The results showed that the half-lives of kresoxim-methyl in green tobacco leaves and soil were 1.2–5.3 days and 6.7–10.4 days, respectively. At harvest, kresoxim-methyl residues in cured tobacco leaves samples collected 21 days after the last application at the recommended dosage were below 1.0 mg kg –¹. These results could help establish appropriate application frequency and harvest intervals in the use of kresoxim-methyl on tobacco plants.
Agid:
4584706