Study On Enantioselective Accumulation And Degradation Of Dinotefuran In Earthworm

The use of pesticide dinotefuran is closely related to environmental safety.Dinotefuran has some differences in enantioselectivity in some biological processes.Studying the selectivity of pesticides has important implications for the rational production of pesticide commodities,the proper use of consumers,and the assessment of environmental safety and ecotoxicology.In this dissertation,the optimum conditions for the resolution of the chiral pesticide dinotefuran enantiomers were determined by optimizing the mobile phase,modifiers,and column temperature conditions.An ultra performance liquid chromatography tandem mass spectrometry for the determination of dinotefuran and its enantiomers was established.Afterwards,the established method was used to verify the method for the determination of dinofuran,a chiral pesticide in soil and alfalfa.The average recovery of dinotefuran in different matrixes was 88.2-105.9%with relative standard deviations of 0.8%-13.5%.The linear correlation coefficient of dinotefuran in the concentration range of 0.001-0.5 mg·kg^-1was R²>0.995.The limits of quantification for natural soils,artificial soils,and earthworms were all 0.01 mg·g^-1.The instrumental detection limit of the liquid instrument used was 0.005mg·kg^-1.This method meets the existing limit standards and requirements.Next,according to the OECD 317 criteria and applying the chiral separation method established above,the behavior of dinotefuran accumulated and degraded in the earthworms was studied under the conditions of two different types of soil substrates:natural soil and artificial soil.The two enantiomers of dinotefuran accumulated at different speeds in the earthworms in different soil.Compared to natural soils,S-Dinotefuran can accumulate more quickly in the earthworms under the conditions of artificial soil cultivation,but the degradation is also slow due to its high cumulative concentration.Under natural soil conditions,the half-life of S-dinotefuran amine in the earthworm was 5.9 d,while the degradation half-life of R-enantiomer was 5.6 d;In the artificial soil,the degradation half-life of S-enantiomer was 9.2 d,and the degradation half-life of R-enantiomer was 5.1 d.In addition,the enantiomer fraction value EF was studied and analyzed from this experiment.In accumulation that the EF value>0.5 was found,indicating that the chiral pesticide dinotefuran have stereoselectivity in the process of soil accumulation and degradation.However,enantioselectivity in natural soils is not very obvious.and they are in the same soil substrate conditions,the two enantiomers of dinotefuran have different degradation rates,and the S-dinotefuran degradation is slower than dinotefuran amine R monomer,which may cause certain potential harm to the life of earthworms.