Degradation Of Novel Pesticide HNPC-A3061in Chinese Cabbage-soil Ecological System

Brochlorfenapyr testcode：HNPC-A3061, chemical name:1-(2-chloroethoxy methy l-4-brom-2-(4-chl orophenyl)-5-tirfluoromethylpyrrol-3-nitrile, is a novel pyrrol insecticidediscovered by Hunan Research Institute of Chemical Industry. Currently, the relevantresearch related to the pesticide residue and photochemical degradation of HNPC-A3061hasnot been reported. For the security of the HNPC-A3061applied on agricultural, the followingresearch we have completed:(1) The analysis method of HNPC-A3061in environmentalmedia;(2) Photochemical degradation dynamics of HNPC-A3061in cabbage and soils;(3)Final residues of HNPC-A3061in cabbage and soils;(4) explore the photochemicaldegradation of HNPC-A3061in different solution. The main results are as follow:1. The gas chromatographic method was described for the determination ofHNPC-A3061in cabbage and soil. Soil samples were extracted with acetonitrile,dichloromethane extraction, cabbage samples were extracted with acetonitrile, salting-out,and then purified by the column filled with the Florida silica-carbon mixture (mass ratio50:1), and the HNPC-A3061residues in cabbage and soil samples were quantified by GCequipped with HP-1stainless steel column and ECD detector.There appeared a excellentlinear relationship between the response values (peak area) of HNPC-A3061and its massconcentrations in the concentration ranged from0.01to10mg/L with the linear correlation of0.9995. At the spiked concentration of0.01～1.0mg/kg, the average recovery rate ofHNPC-A3061in cabbage and soil sample was in the range of96.0～102.4%, and coefficientof variation was3.4～8.1%. The LOD of this method was2×10-11g, and the LOQ0.01mg/kg. The method was simple, fast, and very sensitive with good accuracy in compliancewith pesticide residue analysis.2. Field experiments were conducted to study the photochemical degradation dynamicsof HNPC-A3061in Chinese cabbages and soils from Hunan, Hebei and Jiangsu during thetwo years using gas chromatography-electron capture detector (GC-ECD). Results showedthat the half-life of HNPC-A3061was5.28,5.14,6.16d in Chinese cabbages, and13.05,7.87,11.12d in soils from Hunan, Hebei and Jiangsu in2012, respectively; The half-life ofHNPC-A3061was7.17,6.42,10.73d in Chinese cabbages, and2.75,2.32,5.94d in soils fromHunan, Hebei and Jiangsu in2013, respectively. indicating that HNPC-A3061was a lowtoxic and non-persistent pesticide based on pesticide residue classification of China.3. The results showed that: The maximum final residue of HNPC-A3061in Chinesecabbages and soils at14d after the last application was0.290mg/kg and0.141mg/kg.respectively, when spaying3～4times with the recommended dosage of18g a.i./ha and1.5 times dosage27g a.i./ha, and lower than the MRL value of1.0mg/kg of the same classinsecticide chlorfenapyr in Chinese cabbages established by US EPA, which suggested thatthe MRL value of HNPC-A3061in Chinese cabbages should be1.0mg/kg and thepre-harvest interval14d based on0.5mg/kg of MRL of CAC and China.4. The UV lamp and xenon lamp as light source, research the photochemical degradationdynamics of HNPC-A3061in different solvents. GC-ECD was used for the qualitative andquantitative analysis, study on the photodegradation products with GC-MS. The order ofphoto chemical degradation rate in different solvent is Hexane＞Methanol＞water＞acetonitrile, but, hardly degradation in acetone. the major degradation pathways ofHNPC-A3061are oxidation reaction and hydrolysis reaction. The initial concentration ofHNPC-A3061are negatively correlated wth the photolysis rate in the same solvent, caused ofthe light are limited for every unit. compared between the different light sourece, theHNPC-A3061are degradated more faster in uv light than xenon light, The main factors toaffect the degradation rate are the light source and the type of solvent. In summary, thedegradation of HNPC-A3061impacted by light source, solvent, temperature, initialconcentration.