The Analysis Of Some Pesticide Residue And Sulfoxaflor Degradation In Greenhouse Vegetables In Turpan

The important pests and diseases of vegetablesand the current status of pesticides application are systematically investigated at greenhouse in Turpan,Xinjiang.The types,distribution and main sources of pesticide pollutants of vegetables are analyzed and monitored.At the same time,sulfoxaflor as a represent of pesticide,the degradation dynamics in vegetable and soil were studied.The paper provides basic data for the management of pesticide pollutants of greenhouse vegetables in Turpan.The main results are as follow:（1）Botrytis cinerea,Pseudoperonospora cubensis（Berk.et Curt.）Rostov,and Sphaerotheca fuliginea are main diseases,and Bemisia tabaci（Gennadius）,Liriomyza,Spodoptera exigua Hiibner and Lipaphis erysimi（Kaltenbach）etc are main pests.And Bemisia tabaci（Gennadius）is still the dominant population in Turpan greenhouse vegetables.（2）According to the investigation among 101 farmers in the four townships in Turpan and found that:Pesticides and fungicides are used in different proportions in the growing seasons of spring and autumn.The fungicide is used in spring more frequentlyat 53.47%,and about 1.9%of farmers do not carry out chemical control.While in autumn the insecticides are widely usedwith the propotion of 79.20%,and generally using is approximately 4⁶times perseason,which accounts for 52.48%of the survey.By contrast,farmers constitute 78.21%with intervals of 7¹0 d of pesticides application,and those using pesticides over 10 days represent 20.79%.There are different types of pesticide residues in vegetables during the growing seasons of spring and autumn as well Although fungicide is more popularly used by framers in the spring,most of them were not detected oexpcet the propamocarb hydrochloride was detected with residues about 0.03 mg/kg and 0.07 mg/kg respectively on April and May.The residues of acetamiprid were found in two townships on November,at 1.58 mg/kg and 2.18 mg/kg respectively.（3）Based on the data of pesticide application and residue detection,the soil ecological and ecological risk values of eight pesticides in the fixed greenhouse are obtained from the five investigation sites in Turpan.Imidacloprid,acetamiprid,phoxim,pyrimethanil,chlorothaloniland other pesticides pose higher risk to the soil ecology after application,especially the imidacloprid with the biggest risk value,at 113.89.（4）A method for the determination of sulfoxaflor residue in melons,eggplant and soil samples is built by uitra-high performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS）based on GB/20769.Samples of melon,eggplant and soil are initially extracted with acetonitrile,salting out by NaCl,cleaned up by aminopropyl（NH₂）cartridge,eluted by methanol and dichloromethane（5:95）,metered by methanol and water（1:1）.After filtered with a 0.2μm membrane,the resulting samplesdetermined by UPLC-MS/MS performing on negative electrospray ionization and the multiple reactions monitoring mode（MRM）.Thematrix-matched external standard calibration curves are used for quantitative analysis.The added recoveries are between 77.76%¹07.76%in the concentration range of50⁵00μg/L,and the relative standard deviations（RSD,n=6）are in the range of2.56%⁶.44%.（5）The amount of 300 g/hm² of 50%sulfoxaflor WG was applied to the melon,eggplant and soil in the greenhouse,and the initial deposition amount of the peel,pulp and leafat 0.11 mg/kg,0.02mg/kg and2.58 mg/kg respectively.The initial deposition amount of eggplant and leaf is 0.10 mg/kg and 4.04 mg/kg respectively.The initial deposition amount of soil is 0.01 mg/kg.The degradation dynamics of the agents in the total fruit,leaf of the melon,eggplant and the soil accorded with the first order kinetic equation,and there was no significant difference in the half-life between the two crops.The half-lives of the peel,pulp and leaves of cantaloupe are 9.46 d,7.41 d and 19.86 d respectively.The half-lives of eggplant fruit and eggplant leaves are 5.67 d and 13.54 d.The half-life in the soil is 9.23 d.