| Diethyl aminoethyl hexanoate(DA-6)is a kind of plant growth regulator,which is widely used to improve crop yield and quality.Due to its remarkable efficacy,the amount of DA-6 usage gradually increases in recent years.However,the maximum residue limits of DA-6 in environment and the environmental behavior have not been fully clarified.Therefore,it is necessary to establish a series of analytical methods for DA-6 determination and investigate the DA-6 residue tests.In this study,analytical methods of DA-6 in multimedia were developed,and applied to the determination of samples that collected in the soil,water-sediment system degradation tests and apple field trials.According to the test data,the residue degradation and dissipation rules of DA-6 in multimedia were studied,which provided scientific basis for the environmental safety evaluation and safe use of DA-6 in crops.The main research achievements are as follows:1.The chromatography-FID(GC-FID)analytical methods of DA-6 in water,soil and sediment were developed and validated.The above media were extracted by acetone or and followed by evaporation and reconstitution.The validation results showed that,the correlation coefficients(r~2)was 0.997,the recoveries of the methods in water,soil and sediment were 87.5%～98.8%,70.4%～73.3%and 90.9%～104.4%,respectively.The relative standard deviations(RSDs)were 7.8%～13.2%,7.0%～9.5%and 3.8%～6.5%,respectively,the limitation of detections(LODs)were 0.02 mg/L,0.08 mg/kg and 0.03 mg/kg,respectively.The gas chromatography-EI-mass spectrometry(GC-EI-MS)analytical methods of DA-6in fish and apple were developed and validated.DA-6 in fish was extracted by acetonitrile and detected,and in apple was extracted by heated water and followed by liquid-liquid extraction by dichloromethane.The validation results showed that,the recoveries of DA-6 in fish and apple were 106.8%～108.2%and 74.4%～86.5%,respectively.The RSDs were 7.6%～10.0%and 3.8%～5.2%,respectively.The LODs were 0.003 and 0.0024 mg/kg.The ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)analytical methods of DA-6 in apple,rice,rice husk and rice straw were developed and validated.The validation results showed that,the recoveries of DA-6 in apple,rice,rice husk and rice straw were 102.1%～106.8%,74.1%～88.5%,99.5%～106.4%and82.1%～89.5%,respectively.The RSDs were 6.6%～10.1%,7.3%～9.4%,7.2%～9.5%and5.6%～13.1%,respectively.The LOD were 0.0024,0.0024,0.0033 and 0.0033 mg/kg,respectively.All the methods have satisfactory linear relationships,the recoveries,RSDs and LODs meeting the requirements of DA-6 residue analysis.2.The degradation tests of DA-6 in soil under anaerobic conditions and in water-sediment systems under aerobic conditions were conducted.The results indicated that,the degradation of DA-6 in Jiangxi red soil,Northeast black soil and Taihu paddy soil were all fitted into the first order degradation kinetics,the half-lives were 2.4,1.3 and 1.2 days,respectively.The degradation of DA-6 in river and lake water-sediment systems were fitted into the first order degradation kinetics,the half-lives in two systems were 0.11 and 1.1 days,respectively.DA-6 belongs to easily degradable pesticides in soil and water-sediment systems.Residue dissipation and final residue field trials of DA-6 in apples were conducted in Shanxi,Anhui and Tianjin within one year.The results of residue dissipation trials showed that the dissipation of DA-6 in apple was fitted into first order degradation kinetics,the half-lives in Shanxi,Anhui and Tianjin were 1.8,2.0 and 6.3 days,respectively.In the final residue trials,samples were collected after the last application 10,20 and 30 days.The supervised trials median residue(STMRs)at three places were all 0.008 mg/kg.The dietary risk assessment of DA-6 was conducted according to the final residue trial data.The results indicated that DA-6 does not pose an unacceptable healthy risk to Chinese general population under long-term consumption.The recommended safety interval is 10 days. |
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