Research On The Residue Of Fenpyrazone In Sorghum And Its Adsorption And Migration In Soil

Sorghum has been an important food crop in China since ancient times,and after the founding of the People’s Republic of China,with the development of agriculture and the improvement of people’s living conditions,although sorghum is rarely used as a staple food,it is still needed as a raw material for feed and winemaking.Due to the progress of feed and brewing industry and the establishment of production system,the quality and yield requirements of brewing sorghum are increasing;Moreover,because of its fast growth rate,short growth cycle,high nutritional value,and a certain amount of crude protein,sorghum can be used as a raw material for the production of silage.Although China’s self-produced sorghum can meet the output demand of sorghum for brewing,the demand for sorghum for brewing in China is still increasing,and a considerable part of the sorghum needed by animal husbandry comes from foreign imports.In order to ensure China’s food security,sorghum production should also be gradually increased,but the growth period of sorghum overlaps with the vigorous period of weed growth,resulting in sorghum planting process prone to grass damage,but the active ingredient of herbicides registered on sorghum in China is mostly atrazine,herbicides alone are easy to cause the emergence of resistance,in order to reduce the impact of grass damage on sorghum yield,it is necessary to register new herbicides on sorghum.In this study,the digestion dynamics of fenpyrazone in sorghum plants and soil were studied by establishing a residue analysis and detection method for fenpyrazone on sorghum,and the final residue of fenpyrazone in sorghum and soil was determined,which provided data support for the use of fenpyrazone on sorghum.The adsorption characteristics and migration of fenpyrazone in different soils were studied,which provided a theoretical basis for the risk assessment of the environment of fenpyrazone:1.An HPLC-MS/MS residue analysis method for fenpyrazone in sorghum plants,sorghum and soil was established.The mass spectrometry conditions and chromatographic conditions were optimized,acetonitrile and（0.1%formic acid+5 mmol/L ammonium acetate）purified aqueous solution were used as mobile phases for gradient elution,HPLC-MS/MS method was detected and analyzed,and external standard quantitative.The extractants and purifiers in the pretreatment process were optimized,and the sorghum plants,sorghum and soil samples were extracted by acetonitrile and purified water mixed solution with 0.2%formic acid,and sorghum plants were purified by 10 mg C₁₈+10 mg GCB+100 mg anhydrous magnesium sulfate,100mg PSA+5mg GCB+100 mg anhydrous magnesium sulfate purified sorghum,and 10 mg PSA+100 mg anhydrous magnesium sulfate was used to purify sorghum plants.The linear relationship between fenpyrazone in the range of 0.001～1 mg/L was good,and the correlation coefficient r was greater than 0.999.The recovery rate of fenpyrazone in three matrices ranged from 88.23%～99.33%,and the relative standard deviation ranged from 1.4%～5.1%.2.The digestion dynamics and final residue of fenpyrazone on sorghum were clarified.The field trial was carried out in Changchun City,Jilin Province,Heilongjiang Province and Chifeng City,Inner Mongolia in 2022,and the final residue test used 25%fenpyrazone and atrazine OD at doses of 1125 and 1687.5 g a.i./ha,and the residual digestion dynamic test application dose was 1687.5 g a.i./ha,and at the 3～5 leaf stage（weed 2～5 leaf stage）after sorghum seedlings,the stem and leaf spray was applied 1 time,and samples were taken according to the set time.The experimental results showed that the half-life of fenpyrazone in sorghum plants and soil was between 1.0～1.6 d,and fenpyrazone was an easily degradable pesticide(T_1/2<30 d).The final residue of fenpyrazone on sorghum and soil was less than 0.01 mg/kg.3.The adsorption and migration characteristics of fenpyrazone in different soils were clarified.The adsorption behavior of fenpyrazone in red loam,black soil,brown soil,paddy soil and aquic soil was studied by oscillation equilibrium method,and the experimental results showed that the adsorption kinetics of fenpyrazone in five soils could be nonlinear fitted by Weber-Morris intraparticle diffusion model,and the correlation coefficient was between0.87～0.94.Six concentrations of 1,5,10,15,20 and 25 mg/kg were set for adsorption isothermic test,and the adsorption isothermal curves of the five soils could conform well to the Freundlich model.The results showed that the mobility of fenpyrazone on five kinds of soil was studied by soil thin layer chromatography,and the test results showed that fenpyrazone stayed at30～60 mm on the soil sheet,and according to the Rf value,it was judged that fenpyrazone was a non-mobile pesticide in the five soils,and the risk of polluting water sources by migration was small.