Detection Technology Of Exianliumi Residues In Several Vegetables

In agricultural production,pests and diseases affect the yields of crops.In order to control and eliminate pests and diseases and ensure agricultural production,pesticides are increasingly used.The level of pesticide residue becomes an important indicator of food safety and quality with the increase of food safety requirements.Therefore,the establishment of detection methods of various pesticides residue has been paid more and more attention.China is a big agricultural country,and its Vegetable production is the first in the world.Common vegetables such as cucumbers and peppers have high nutritional value and are deeply loved by people.Various types of vegetables are deeply endangered by nematodes.Exianliumi is a novel pesticide for the control of nematodes in vegetables.At present,the detection technology of exianliumi residues in vegetables is few.So it is great scientific significance and practical significance to construct detection technology of exianliumi residues in common vegetables.In this thesis,the detection technology of exianliumi residues in cucumber,pepper,tomato,zucchini,eggplant and cowpea were established.Quantitative analysis was performed by high performance liquid chromatography（HPLC）.The chromatographic detection conditions were as follows:the detection wavelength of the UV detector was 227 nm,C18 analytical column,the flow rate was 0.6 mL min-1,the injection volume was 20 L,and the temperature was room temperature.When the concentration of exianliumi is 0.01～10 mg L^-1,there is a good linear relationship between the concentration and the peak area,the correlation coefficient is 0.9994.When the signal-to-noise ratio（S/N）is 3,the minimum detection amount of the instrument for detecting exianliumi is 0.2 ng.Cucumbers,peppers,and tomatoes were extracted with acetone.Two drops of formic acid are added during cucumber extraction.Zucchini,eggplant,and cowpea used acetonitrile as the extraction solvent.After extraction,the organic solvent was concentrated to remove.The residual solution in cucumber,pepper,tomato,and zucchini was extracted using traditional liquid-liquid extraction.Eggplant and cowpea were treated directly with QuEChERS pretreatment by adding PSA,sodium chloride and anhydrous sodium sulfate.After extraction,cucumber was purified by adding PSA.Zucchini is purified by silica gel column chromatography.The mixed solution of methanol and water was used as the mobile phase of HPLC in cucumber,pepper,zucchini,and eggplant.The mixed solution of acetonitrile and water was used as the mobile phase of HPLC in tomatoes and cowpeas.Based on the blank matrix response as the standard,the limit of detection（LOD）and limit of quantification（LOQ）of exianliumi in cucumber,tomato,zucchini,eggplant,and cowpea samples were 0.02 mg kg^-1 and 0.05 mg kg^-1 at S/N=3 and S/N=10,respectively.The detection limit and quantitation limit in pepper were 0.01 mg kg^-1 and 0.03 mg kg^-1,respectively.Finally,the refrigeration stability of exianliumi in cucumber and pepper matrix was examined.The concentration of exianliumi at 0.5 mg kg^-1 was used as the test concentration for the refrigeration stability of cucumber.During 180 days of storage,the average recoveries of of exianliumi in the stored samples was 86.90-100.00%,and the average spiked recoveries of of exianliumi in the quality control samples was 92.77-98.61%,RSD is 0.77-6.29%.The accuracy and precision of the detection results can meet the requirement for the analysis of pesticide residues in the environmental samples.The highest degradation rate of exianliumi is 13.1%and less than 30%during storage.The exianliumi is stable in cucumber,and meets NY/T 3094-2017 standard requirement.When cucumbers were stored at-20℃ for 21 d,and the average recovery of exianliumi was greater than 95%.In order to ensure the accuracy of the experimental results,it is recommended that the cucumber be tested within 21 days of storage to reduce the loss of exianliumi.The mass concentration of exianliumi at 0.3 mg kg^-1 was used as the test concentration of pepper refrigeration stability.The pepper samples were stored at-20℃ for 120 days,and the average storage recoveries of exianliumi were 98.66-105.59%.The average spiked recovery of exianliumi is 96.77-105.03%,and the RSD is 0.13-3.62%in the quality control samples of pepper.The accuracy and precision of detectiong can meet the requirement of pesticide residue analysis in the environmental sample.The highest degradation rate of exianliumi in pepper is 1.416%during storage.With the increase of storage time,the exianliumi in pepper did not decrease significantly.Although the recovery rate is slightly reduced,the total degradation rate is less than 30%,indicates that the exianliumi is very stability in pepper.The results meet the requirements of the NY/T 3094-2017 standard.The peppers were stored at-20℃ for 120 days,and the average recovery of exianliumi was greater than 95%.Therefore,in order to ensure the accuracy and scientificity of the experimental results,peppers can be tested within 120 days of storage to reduce the loss of exianliumi.