title: Degradation kinetics of the insecticide spinetoram in a rice field ecosystem.
abstract: The fate of spinetoram was studied in a rice field ecosystem, and an efficient method for the determination of spinetoram (XDE-175-J and XDE-175-L) in soil, rice straw, paddy water, husk and brown rice was developed. Spinetoram residues were extracted from samples with a salting out extraction procedure. The extracts were diluted with 0.10% formic acid in water and analysed with liquid chromatography tandem mass spectrometry (LC-MS/MS) on a Waters Acquity BEH C18 column. The calibration curve was linear in the range 0.125-100 μg L(-1) and r>0.999. The average recovery was 82.9-89.0% from soil, 78.5-92.1% from rice straw, 93.6-100.3% from paddy water, 79.1-87.9% from brown rice and 72.7-82.9% from husk. The relative standard deviation (RSD) was less than 10%. These results are all within the accepted range for pesticide residue determination. The field test results showed that spinetoram degradation in paddy water, soil and rice straw coincided with C=0.0132e(-1.9685t), C=0.0308e(-0.1018t) and C=0.8530e(-0.6223t), respectively. The half-lives of spinetoram in paddy water, soil and rice straw were 0.35, 6.8 and 1.1 d, respectively. The final residue level was lower than the maximum residue limit (MRL) of 0.05 mg kg(-1) for spinetoram in rice with a harvest interval of 7d. A dosage of 450 mL ha(-1) was recommended, which can be considered safe for human beings and animals. The results of this study will contribute to establishing the scientific basis of the dosage of spinetoram for agricultural fields.
authors.affiliation: Shanghai Agriculture Technical Extension Service Center, Shanghai 201103, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.affiliation: The Ningbo Academy of Agricultural Sciences, Ningbo 315040, PR China.
authors.forename: Guo
authors.initials: G
authors.lastname: Chen
authors.affiliation: The Ningbo Academy of Agricultural Sciences, Ningbo 315040, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.affiliation: The Ningbo Academy of Agricultural Sciences, Ningbo 315040, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: The Ningbo Academy of Agricultural Sciences, Ningbo 315040, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: The Ningbo Academy of Agricultural Sciences, Ningbo 315040, PR China.
authors.forename: Ting
authors.initials: T
authors.lastname: Yang
authors.affiliation: The Ningbo Academy of Agricultural Sciences, Ningbo 315040, PR China. Electronic address: wupaddyfield@tom.com.
authors.forename: Yin-Liang
authors.initials: YL
authors.lastname: Wu
mesh_terms: D000383:Agriculture / Q000379:methods; D002853:Chromatography, Liquid; D006207:Half-Life; D007306:Insecticides / Q000032:analysis / Q000737:chemistry*; D007700:Kinetics; D018942:Macrolides / Q000032:analysis / Q000737:chemistry*; D012275:Oryza / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D007306:Insecticides; D018942:Macrolides; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; C548262:spinetoram
keywords: Degradation; Residue; Rice; Soil; Spinetoram