Behaviour And Dietary Exposure Assessment Of Three Insecticides In The Planting And Decocting Of Cortex Moudan

The safety of traditional Chinese medicine?TCM?is a key factor affecting the quality and efficacy,which also seriously restricts the modernization and internationalization.The use of pesticides in the process of TCM has played a positive role in the prevention and control of pests and disease,increasing the output of Chinese medicinal materials and ensuring the economic benefits of the Chinese medicinal industry.However,the long-term use and abuse of pesticides not only cause serious environmental pollution,but also reduce the efficacy of TCM.In view of the lack of good pesticide usage standards and related risk assessment in agriculture in China,this study selected Cortex moudan as the research object.There were 28 insecticides analyzed by high performance liquid chromatography-mass spectrometry?UPLC-MS/MS?and market samples were collected to investigate possible pesticide contamination.The effects of decoction on pesticide residues in TCM were systematically studied.On the basis of market monitoring data and processing factors?PFs?of pesticide residues,we assessed the possible risks to consumers.In addition,we also studied the residual behavior of pesticides in the field,and identified the appropriate pesticides and their standardized use.The results have important theoretical and practical value for the scientific evaluation of the safety of TCM,the strengthening of the risk management of TCM pesticide residues,and the improvement of the quality and safety of TCM.The main results are as follows:1.Establishment of a multi-residue analysis method for 28 kinds of pesticides in C.moudan decoction piecesBased on Qu ECh ERS,a multi-residue analysis method was developed for simultaneous detection of 28 insecticides in C.moudan.The correlation coefficient?r²?was 0.989-0.998,and the detection limit?LOD?and quantification limit?LOQ?were 0.01-2.02 and 0.03-6.17,respectively.At the addition level of 10-200 g/kg,the addition recovery rate of 28 pesticides was 60.62-118.25%,and the relative standard deviation?RSD?was 1.2-18.45%,indicating good repeatability.The matrix effect of 28 pesticides in C.moudan decoction slices was21.53%to 96.45%,indicating that the matrix effect had exceeded an acceptable range.Therefore,in subsequent experiments,in order to avoid the quantification deviation caused by matrix effect,we prepared matrix matching standard solution for matrix effect compensation.2.Distribution of pesticide residues in prepared slices of C.moudanThe results of pesticide residues in 101 Chinese C.moudan decoction pieces showed that a total of 8 insecticides were detected,namely,octyl thiophosphorus,chlorpyrifos,cypermethrin,acetamididine,imidacloprid,thiamethoxam,almexide,and methylphosphosulfoxide,with the detection rate of 87.13%.Among them,86.14%of the samples detected more than 2 pesticide residues at the same time.It is important to note that two other highly toxic pesticides are also frequently detected,namely chlorpyrifos and anthracidazole.The detection rate and concentration of chlorpyrifos were 51.49%and 2.96-81.73 g/kg,respectively,and the detection rate and concentration of chlorpyrifos were 72.28%and 0.65-5.09 g/kg,respectively.It can be seen that attention should be paid to the problem of pesticide residues on C.moudan decoction pieces,so as not to affect the quality and market of Dan PI decoction pieces.3.Dissipation of phoxim,chlorpyrifos and Fenpropathrin in C.moudan plant under field conditionThe TCM decoction of C.moudan follows the management standard of TCM decoction room in medical institutions.The results showed that the PFs of the pesticide in the cortex oleracea was 0.0049?0.0602 and 0.0742,indicating that the TCM decoction was effective in removing some pesticide residues,and the digestion rate was more than 80%.At the same time,note that TCM decoction can concentrate residues and transfer them to more toxic metabolites.With the extension of decoction time,the residual quantity of TCP and in TCM decoction increased at first and then decreased.4.Behavior of phoxim,chlorpyrifos and fenpropathrin in C.moudan during decoctingIn the dynamic experiment of pesticide residue,the degradation trend of pesticide in root of C.moudan was first order kinetics.The half-lives(t_1/2)of thiophane,chlorpyrifos and cypermethrin were 12.160 d,11.176 d and 11.874 d,respectively.At the last 14 d of the sampling period,residues of all three pesticides were lower than MRLs in other crops.5.Risk assessment of dietary exposure to the pesticide residues of phoxim,chlorpyrifos and fenpropathrinDietary pesticide exposure was estimated using a point estimation model based on market monitoring data.The results showed that the risk factor?HQ_c?of chronic dietary exposure to pesticides in paederma was 2.09×10^-4-3.65×10^-3.The acute dietary exposure risk factor?HQ_a?of the pesticide in C.moudan was 1.66×10^-4-3.91×10^-4,all within the acceptable range.The results show that some farmers are still using highly toxic pesticides or banned pesticides,which should be taken seriously.This study further calculated the daily pesticide exposure of TCM decoction.Compared with the total chemical concentration for exposure calculation,the risk assessment using the processing factor is less dangerous.The risk assessment of pesticides will be overestimated without considering the decoction effect of TCM.