| The multi-residue analytical method of pyrethroid insecticides on some herbs(Lycium barbarum L,Glycyrrhiza uralensis,Lonicera japonica and Dendranthema morifolium)was set up.In order to investigate dissipation behaviour of Fenpropathrin,Beta-cypermethrin,Lambda-cyhalothrin and Fenvalerate during the infusion process.The resons for difference transfer of pyrethroid insecticides has be Studied;and safety evaluation of pyrethroid insecticides in Lycium barbarum L tea was reported.The main results are as follows.1 The multi-residue analytical method for pyrethroid insecticides in 4 herbal teas and their infusion.The herbal teas samples were extracted with acetonitrile by mechanical shaking and cleaned up by Florisil SPE.The cooled infusion extract was subjected to partitioning with dichloromethane.All the samples were detected by GC-ECD.As the fortified concentration were 0.01~0.5mg·kg-1(herbal teas)and 0.002~0.2 mg·kg-1(infusion),the average recoveries of Fenpropathrin,Beta-cypermethrin,Lambda-cyhalothrin and Fenvalerate in the herbal teas were ranged between 80.2%~110.5%,the coefficient of variation were 2.31%~11.23%;The average recoveries in infusion were ranged between 80.2%~115.4%,the coefficient of variation were 3.03%~ 11.03%.These results showed that the accuracy and sensitivity of themethod meet the requirement of pesticide residue analysis.2 Influence on the transfer of from Lycium barbarum L to infusion in different soaking conditions.The transfer of pyrethroid insecticides from Lycium barbarum L teas to infusion in different soaking conditions(tea/water ratio,infusing times,infusing duraion,and infusing temperature)was studied.The result shows that: the transfer of the 4 pyrethroid insecticides decreased significantly with the increasing of soak times,the transfer of two previous respectively accounted for 85.75%,79.55%,81.65% and 81.19%.The transfer of 4 pyrethroid insecticides increases with the increasing of the infusing duration,4.28%,2.59%,3.69% and 3.42%,the transfer rate remain stable or decrease slightly after 20 minutes.The transfer of 4 pyrethroid insecticides increases with the increasing of the infusing temperature,the transfer rate were respectively 4.21%,2.72%,3.84% and 3.51% at 100 °C the transfer of the 4 pyrethroid insecticides increased with the decreaseing of the tea/waterratio(1:30-1:100).The maximum transfer rates were respectively 4.57%?3.18%?4.41% and 3.18%.3 Influence on the transfer of pesticides from Glycyrrhiza uralensis teas to infusion in different soaking conditions.The transfer of pyrethroid insecticides from Glycyrrhiza uralensis teas to infusion in different soaking conditions(tea/water ratio,infusing times,infusing duraion,and infusing temperature)was studied.The result shows that: the transfer of the 4 pyrethroid insecticides decreased significantly with the increasing of soak times,the transfer of two previous respectively accounted for 85.90%,100%,88.41% and 84.32%.The transfer of 4 pyrethroid insecticides increases with the increasing of the infusing duration,The maximum transfer rates were respectively 3.32%,1.7%,2.91% and2.48%,the transfer rate remain stable or decrease slightly after 20 minutes.The transfer of 4 pyrethroid insecticides increases with the increasing of the infusing temperature,the transfer rate were respectively 3.25%,1.45%,2.65% and 2.43% at100°C The transfer of the 4 pyrethroid insecticides increased with the decreaseing of the tea/water ratio(1:30-1:100).The maximum transfer rates were respectively 3.39%,2.01%,3.08% and 3.11%.4 Influence on the transfer of pesticides from lonicera japonica to infusion in different soaking conditions.The transfer of pyrethroid insecticides from lonicera japonica teas to infusion in different soaking conditions(tea/water ratio,infusing times,infusing duraion,and infusing temperature)was studied.The result shows that: the transfer of the 4 pyrethroid insecticides decreased significantly with the increasing of soak times,the transfer of two previous respectively accounted for 100%,83.86%,100% and 100%.The transfer of 4 pyrethroid insecticides increases with the increasing of the infusing duration,4.28%,2.59%,3.69% and 3.42%,the transfer rate remain stable or decrease slightly after 20 minutes.The transfer of 4 pyrethroid insecticides increases with the increasing of the infusing temperature,the transfer rate were respectively 4.21%,2.72%,3.84% and 3.51% at 100°C the transfer of the 4 pyrethroid insecticides increased with the decreaseing of the tea/waterratio(1:30-1:100).The maximum transfer rates were respectively 6.70%,4.03%,5.97% and 4.91%.5 Influence on the transfer of pesticides from Dendranthema morifolium to infusion in different soaking conditions.The transfer of pyrethroid insecticides from Dendranthema morifolium teas to infusion in different soaking conditions(tea/water ratio,infusing times,infusing duraion,and infusing temperature)was studied.The result shows that: the transfer of the4 pyrethroid insecticides decreased significantly with the increasing of soak times,the transfer of two previous respectively accounted for 89.03%,100%,83.94% and 100%.The transfer of 4 pyrethroid insecticides increases with the increasing of the infusing duration,5.78%,4.02%,5.51% and 5.08%,the transfer rate remain stable or decrease slightly after 20 minutes.The transfer of 4 pyrethroid insecticides increases with the increasing of the infusing temperature,the transfer rate were respectively 5.43%,3.96%,5.23% and 4.87% at 100°C the transfer of the 4 pyrethroid insecticides increased with the decreaseing of the tea/waterratio(1:30-1:100).The maximum transfer rates were respectively 6.30%,3.54%,5.17% and 4.28%.6 The difference transfer of pyrethroid insecticides in herbal teasThe transfer of pyrethroid insecticides at same infusing conditions(1 time,100°C,10 min,1:50)in different herbal teas was compared.There were significant differences between the 4 herbal teas,the transfer of pyrethroid insecticides in lonicera japonica and Dendranthema morifolium is higher than transfer in Lycium barbarum L and Glycyrrhiza uralensis.The transfer rates of the 4 pyrethroid insecticides were also compared.The transfer rates of the 4 from largest to smallest were Fenpropathrin,Lambda-cyhalothrin,Fenvalerate and Beta-cypermethrin.The similar trend was found in the water solubility(Ws)and Octanol-water partition coefficient(Kow)of the 4 pyrethroid insecticides.The Log1/Ws and Log were considered as abscissa,and the transfer rates were considered as ordinate.The linear equations between Log1/Ws with the transfer rates is respectively y=-0.2545x+4.4937,y=-0.2581x+3.5664,y =-0.3174x+ 6.4587 and y =-0.2887 x + 6.2645,correlation coefficients were higher than 0.96.The linear equations between Log Kow with the transfer rates is respectively y=-1.2504x+11.021,y=-1.2822x+10.274,y=-1.4404x+13.807 and y=-1.6078x+14.901,correlation coefficients were higher than 0.97.7 Safety evaluations of pyrethroid insecticides residues in herbal teasLycium barbarum L,for instance the afety evaluations of pyrethroid insecticides residues was given according to the safety evaluation system were made by Wang Yunhao,et al.The safety factors of the 4 pyrethroid insecticides are respectively 179,198,13400 and 1378. |
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