Behavior And Dietary Exposure Assessment Of Selected Insecticides In Paeoniae Radix Alba And Chaenomelis Fructus During Chinese Medicine Processing And Decoction

The cultication scale of medical plants are susceptible to a variety of insect infestations.The use of pesticides for combating insect pests and diseases in Traditional Chinese Medicine(TCM)production has led to the accumulation of pesticide residues and affect the quality of TCM.Aiming at the absence of good agricultural practices for pesticide use and related risk assessment,Paeoniae Radix Alba(PRA),Chaenomelis Fructus(CF)were selected in this study to represent roots and fruits of commonly used TCMs,respectively.The QuEChERS(Quick Easy Cheap Effective Rugged and Safe)-UPLC-MS/MS(ultra-performance liquid chromatography tandem mass spectrometry)method was applied to simultaneously analyse 28 pesticides selected according to the recommendations of local farmers and the existing literature.Then,samples were collected to investigate possible pesticide contamination.Moreover,we focus on the processing and decoction of PRA and CF,systematic study the effects of Chinese medicine processing and decocting on the pesticide residues in TCM.The bioaccessibility of frequently detected insecticides and related impact factor was investigated.Based on the market monitoring data,processing factors(PF)of pesticide residues,we assess possible risks to consumers.Furthermore,we investigated the dissipation behavior of pesticides in PRA and CF under field conditions,and their effect on the pharmacological ingredients of PRA and CF,and clearly the suited pesticides and their standardized use.The results are of great theoretical and practical value for the scientific evaluation of the safety of Chinese medicines,strengthening the risk management of pesticide residues in Chinese medicines,and improvement of the quality and safety level of Chinese medicine.The main outcomes are as follow:1.Analysis method and monitoring survey of pesticide residues in PRA and CFA simple and high-throughput multiresidue pesticide analysis method was developed and validated for a simultaneous 28 residue analysis in PRA and CF based on QuEChERS procedure combined with HPLC-MS/MS.The calibration curves displayed satisfactory linearity with 0.9891-0.9984 of correlation coefficients(r2).The limit of detections(LODs)and limit of quantitations(LOQs)of target compounds were in the range of 0.01-2.02 and 0.03-6.17 μg kg-1,respectively.Satisfactory accuracy was achieved with a recovery of 63.47-113.51%and 65.52-113.50%for PRA and CF,respectively,which were within the ranges expected for residue analysis.The relative standard deviation(%RSD)ranged from 1.57 to 13.46%,indicating good repeatability.Matrix effects(i.e.suppression or enhancement)were in an unacceptable range.Thus,to avoid quantification deviating due to matrix effects,matrix-matched calibration standard solutions were prepared for quantification.The residues in PRA and CF pieces collected from China was investigated using the QuEChERS-UPLC-MS/MS method.Results showed that 8 kinds and 6 kinds of pesticides,such as phoxim,chlorpyrifos,fenpropathrin,and emamectin benzoate,were detected in the PRA and CF pieces.Contamination with>2 detectable pesticides per sample amounted to 100%and 79.82%for PRA and CF,respectively,indicating that the TCM had been exposed to more than one pesticide.Among the pesticides,phoxim was the most commonly detected.The frequency of detection(%)for phoxim in PRA and CF was 41.75%and 68.81%,respectively,and the residual values amounting to 25.22-1199.84 μg·kg-1 and 4.91-913.10 μg·kg-1.Moreover,40.78%and 18.35%of samples containing phoxim exceeded Maximum residue limits(MRLs)in other species(0.05-0.2 mg·kg-1).Notably,several high risk pesticides,e.g.,chlorpyrifos and aldicarb,were frequently detected.The frequency and residue level of chlorpyrifos was 44.95-58.25%and 21.82-40.32 μg·kg-1,respectively,and 7.34-20,39%and 0.72-0.81μg·kg-1 for aldicarb.2.Behavior of pesticide residues in PRA and CF during processingThe processing(eg.,boiling,peeling,and drying)of TCM followed the protocol reported in the Pharmacopoeia of People’s Republic of China and industrial processes,all within warranties of property and quality of TCM.Results showed that the PFs of pesticides in PRA and CF were 0.0002-0.0115 and 0.0092-0.0644,respectively,indicating that TCM processing could be useful for the partial removal of several pesticide residues,with dissipation percentage reaching above 93%.Variation degradation was observed for pesticides,which may be related to relatively low water solubility,high log octanol-water partitioning coefficient(Log Kow)having strong systemic properties,resulting in easier degradation.3.Behavior of pesticide residues in PRA and CF during decoctingThe TCM decocting of PRA and CF followed the protocol reported in the TCM Decoction Room Management in Medical Institutions.Results showed that the PFs of pesticides in PRA and CF were 0.0058-0.0836 and 0.0304-0.0567,respectively,indicating that TCM decocting could be useful for the partial removal of several pesticide residues,with dissipation percentage reaching above 91%.Meanwhile,note that TCM decocting can concentrate residues and onvert residues to more toxic metabolites in TCM.The residues of TCP and clothianidin significantly increased and then decreased in herb decoction liquid with the increasing decoction time.4.Behavior and bioaccessibility of pesticide during in vitro human digestionAs an edible fruit,the bioaccessibility of pesticide residues in CF and the affecting factors using an in vitro test by simulating the human gastro-intestinal tract.Results showed that the bioaccessibility varied for the pesticide types and digestion phase(order of gastric>intestinal>oral).Bioavailability of different types of pesticides was different,imidacloprid(85.22%)and thiamethoxam(67.68%),etc,which suggests that pesticides with high water solubility or low Log Kow values showed relatively high bioavailability.The roles of enzymes were validated,showing that the bioaccessibility of the six pesticides varied according to the α-amylase,pepsin,pancreatin,and bile salt levels.α-amylase showed a gradually increasing effect,whereas a contrary relative bioaccessibility of pesticides was observed for pancreatin.Similarly,in the presence of bile extract and pepsin,the bioaccessibility of pesticides first increased and then decreased followed by slowly levelling out.5.Effect of PF on risk assessment studies with pesticide residuesDietary exposure to pesticides was estimated using a point estimate model based on the market monitoring data.The results showed that long-term consumer exposure values(HQc)of pesticides in PRA and CF ranged from 4.52×10-7-1.30×10-2 and 7.62×10-7-2.54×10-3,respectively;short-term consumer exposure values(HQa)of pesticides in PRA and CF ranged from 3.40×10-6-3.30×10-4 and 3.19×10-6-1.87×10-4,respectively;and hazard index values(HI)of pesticides in PRA and CF ranged from 1.38×10-2 and 4.12×10-3,respectively,and within the acceptable level.Among those pesticides,phoxim and emamectin benzoate was clearly the most influential contributor to HI,accounting for 94.36%and 61.60%in PRA and CF,respectively.The results indicate that some farmers are still using highly toxic and/or prohibited pesticides,which need to pay attention.Dietary exposure to pesticides with the PF of TCM decocting was further calculated in this study.Compared to use the total chemical concentration for exposure calculation,the risk assessment with the PF showed a lower hazard quotient(HQ)value.Without considering the PF of TCM decocting or bioaccessiblity,the risk assessment of pesticides can be overestimated exceed 10-fold.6.Dissipation behavior of phoxim,fenpropathrin,and emamectin benzoate in PRA and CF plant under field conditionFor residue dynamic trials,the concentration of pesticide in PRA root first increased and then decreased followed by slowly levelling out,while the degradation trends of pesticides in the CF followed first order kinetics.The mean half-life(t1/2)of phoxim and fenpropathrin in PRA was 18.24 and 11.18 d,as well as 4.05 and 3.69 d for fenpropathrin and emamectin benzoate,respectively.At the end of the sampling period of 21 d,the final residues of phoxim and fenpropathrin in the PRA were 41.13 μg·kg-1 and 10.32 μg·kg-1,respectively;and he final residues of fenpropathrin and emamectin benzoate in the CF were 63.27 μg·kg-1 and 24.01 μg·kg-1,respectively at the end of the sampling period of 14 d,which were low the respective MRL values in other species.No significant difference in the active constituents of paeoniflorin and the total of ursolic acid and oleanolic acid in PRA and CF,respectively,compared with the blank group and phoxim(paeoniflorin)or emamectin benzoate.Thus,we suggested that phoxim was irrigated at the dosage of 1200 mL/667 m2 for PRA and emamectin benzoate was sprayed twice at the dosage of 20 g/667 m2 for CF,respectively.