Residual Behavior Of Three Pyrethroid Insecticides During The Cultivation,Processing And Decoction Of Nepeta

Pesticide residues are one of the important factors affecting the quality and safety of Chinese herbal medicines.The Chinese medicinal material is a raw medicinal material obtained from the medicinal plant after the initial processing of the medicinal plant.The medicinal material is processed into a traditional Chinese medicine decoction piece,and then decoctioned to form a traditional Chinese medicine decoction for people to take.The processing process of the Chinese medicinal material has significant significance for the pesticide residue.At present,there are few reports on the residual behavior of pesticide residues in Chinese herbal medicines during processing and boiling.In this paper,the method of GC-MS residue analysis of fenpropathrin,lambda-cyhalothrin and beta-cypermethrin on Nepeta was established by QuEChERS method.The residual behavior of three pyrethroid insecticides during the cultivation,processing and decoction of Nepeta was studied.The main findings are as follows:1.Establishment of GC-MS residue analysis method for three insecticides on NepetaThe QuEChERS method was used for sample preparation,and a GC-MS multi-residue analysis method for three pyrethroid insecticides in Nepeta and its decoction was established.The substrate in the Nepeta and its decoction has less than 20%effect on the matrix of the three pyrethroid insecticides.It is classified as a weak matrix effect,so the matrix effect can be neglected when the sample is measured.When the concentration was 0.025 mg·kg-1-2.0 mg·kg-1,the recoveries of test pesticides in Nepeta and its decoction were 85.8-110.2%and 88.8-100.3%,relative standard deviation.(RSD)is 1.29-5.6%and 2.22-4.79%.The detection limits(LOD)and limit of quantitation(LOQ)of the three tested insecticides were 10-25 ?g·kg-1 and 25-50 ?g·kg-1.The results showed that the accuracy,accuracy and sensitivity of the three pesticides in the residue analysis of Nepeta and its decoction solution met the requirements of pesticide residue analysis.2.Dynamic results of residual digestion of three insecticides in the process of Nepeta plantingIn August 2018,in the Nepeta planting base of Beijing Tongrentang(BoZhou)Pieces Limited Liability Company,the field residues of three insecticides,such as fenpropathrin,lambda-cyhalothrin and beta-cypermethrin,on schizonepeta were carried out of test,The recommended doses of 240 g/hm2,37.5 g/hm2 and 54 g/hm2 were used as the recommended doses for fenpropathrin,lambda-cyhalothrin and beta-cypermethrin.The results showed that the original deposition amounts of the three insecticides on Nepeta were 36.66mg·kg-1,4.07mg·kg-1,and 5.80mg·kg-1,respectively.The three insecticides showed a tendency to digest on the Nepeta,and the digestion equations were consistent with the first-order reaction kinetics equation.The equations are y=7884e-0.163x,R2=0.951,y=1047.4e-0.132X,R2=0.96,y=1082.7e-0.133x.R2=0.7964,The rates of digestion of the three insecticides on Nepeta were slightly different,with half-lives of 4.2 days,5.3 days,and 5.2 days.3.Changes in residual levels of three insecticides during the processing of NepetaThe residual processing effect of three pyrethroid insecticides on the processing of Nepeta.The processing of Nepeta is mainly for cleaning and drying.In the cleaning experiment of Nepeta,the actual cleaning time of the schizonepeta was determined by reference to the actual cleaning time of the schizonepeta decoction processing plant,which was set to 10s,20s,30s,45s and 60s.The residual tendency of cypermethrin,lambda-cyhalothrin and beta-cypermethrin in the cleaning process is reduced.The concentrations of the three insecticides before washing were 4.96 mg·kg-1,1.22 mg·kg-1,2.76 mg·kg-1.During the cleaning process,the loss rates of the three insecticides on Nepeta were 20.90-49.79%,13.94-57.85%,37.01-66.04%.The processing factors of the three insecticides in Nepeta during the cleaning process were 0.50-0.79,0.42-0.86,and 0.34-0.63.Refer to the drying method of schizonepeta in the Chuzhou Chinese Herbal Pieces Processing Factory(dry or low temperature drying).In the drying experiment of Nepeta,four dry treatments such as dry drying,drying,40? drying and 60? drying were set.The results show that the time required for the dry treatment of the four drying treatments is 7-10 days.Under this treatment,the residual amount of fenpropathrin decreased,and the residual amount of lambda-cyhalothrin and beta-cypermethrin increased;The drying time at 40 0C and the drying time at 60? are 2d and 1d.Among them,the residual amount of cypermethrin,lambda-cyhalothrin and beta-cypermethrin in the drying treatment at 40? was significantly increased and the maximum increase was 1.40 times,1.59 times and 1.53 times of the residual amount before drying treatment.The minimum time required for drying treatment was 2-3 h,and the residual amount of the three insecticides increased under the treatment,which were 1.29 times,1.31 times and 1.35 times of the residual amount before drying treatment.The processing factors of the three insecticides in the four dried treatments were 0.95-1.40,1.15-1.59,1.29-1.53.4.Changes in residual levels of three pesticides under different treatments of Nepeta decoctionThe residual effect of the schizonepeta decoction on the residual pyrethroid insecticides.The decoction of schizonepeta follows the principle of second decocting after soaking.In this paper,different time parameters were set according to the boiling standards of Nepeta to carry out the soaking experiment and boiling experiment of Nepeta.Before the immersion test,the concentrations of the three insecticides were 3.09 mg·kg-1,0.83 mg·kg-1,and 1.63 mg·kg-1.In the immersion experiment,the loss rates of cypermethrin,lambda-cyhalothrin and beta-cypermethrin were 25.75-88.82%,43.24-93.03%,63.23-92.66%,Processing factors are 0.11-0.74,0.07-0.57,0.34-0.63;The change in the residual amount of the three insecticides in the mustard decoction was reduced during the first decoction of Nepeta.The content of fenpropathrin in the decoction liquid was 0.038 mg in the first decoction for 3 min,and the content of fenpropathrin in the decoction liquid gradually decreased with the boiling time,after boiling for 15 min.The minimum is 0.012 mg.No lambda-cyhalothrin and beta-cypermethrin were detected in the decoction during the first boiling.At the second decocting,the change in the residual amount of the three insecticides in the cooking broth was similar to that in the first decocting.At the first decoction of Nepeta,the residual levels of the three insecticides in Nepeta were reduced,and the loss rates were 19.08-50.64%,24.62-60.54%,33.94-77.35%.The processing factors are 0.45-0.82,0.40-0.75,0.23-0.66;The residual levels of the three insecticides in the mustard mustard were similar to those in the first decoction.The loss rates were 58.73-82.63%,43.56-78.42%,35.54-70.92%.The processing factors are 0.19-0.41,0.22-0.56,and 0.29-0.64.In this paper,three GC-MS residue analysis methods for insecticides in Nepeta and its decoction were established.The field digestion of three tested insecticides on Nepeta was studied.At the same time,the effects of processing and boiling on the residues of three tested insecticides in Nepeta were studied.It has important reference value for the safety evaluation of pyrethroid insecticides in the production and processing of whole grass Chinese herbal medicines.