Establishment Of Residue Limit Standard And Dietary Risk Assessment Of Ningnanmycin In Ginseng

As a traditional Chinese medicinal material in china,ginseng has a medicinal history for thousands of years,it not only has anti-fatigue,anti-oxidation and other health care functions,but also has pharmacological functions such as regulating blood sugar and improving human immunity.It is one of the special crops used in both food and medicine in our country.Ginseng has a long growth cycle,which makes it vulnerable to pathogens,pests,weeds and other pests,resulting in a loss of ginseng yield up to 20%～50%.Therefore,many chemical pesticides are widely used in the process of ginseng cultivation to improve the production and quality of ginseng.However,the excessive use of chemical pesticides has caused environmental pollution,the pesticide residues produced by repeated use of medicines for many years,while affecting the quality of ginseng,it also endangers human health.In order to improve the yield and quality of ginseng,it is necessary to stipulate the scope,method and dosage of pesticides on ginseng,formulate pesticide residue limit standards on ginseng,guarantee the safe production of ginseng.In this study,a method for the analysis and detection of ningnanmycin residues in ginseng was established to study the residual digestion of ningnanmycin in ginseng plants and soil.The field samples were obtained through the practical application of ningnanmycin in ginseng field.The final residues of ningnanmycin in fresh ginseng,dried ginseng,ginseng plant and soil were determined,which provided scientific basis for the establishment of the maximum residue limit of ningnanmycin on ginseng.According to the current national standards,the dietary risk of ningnanmycin on ginseng was evaluated,which provided a strong guarantee for the safe consumption of ginseng.1.A high performance liquid chromatography tandem mass spectrometry（HPLC-MS/MS）method was developed for the determination of ningnanmycin residues in fresh ginseng,dried ginseng,ginseng plant and soil.The mass spectrometry conditions and flow matching ratio were optimized,and the extraction solvent,purification conditions and concentration conditions were optimized.The sample was extracted with formic acid water mixture,purified by PLS+PXC solid phase extraction column,separated by XSelect（?）HSS T3 column,and detected by high performance liquid chromatography-tandem mass spectrometry.In the range of 0.05～2.0 mg/L,ningnanmycin had a good linear relationship,and the correlation coefficient r was greater than0.9983.The average recovery rates of ningnanmycin in fresh ginseng,dried ginseng and ginseng plants and soil were 78.4～104.8%,and the relative standard deviations（RSD）were between1.4%and 10.2%.2.Field trials were carried out in Baishan City,Jilin Province and Huanren Manzu Autonomous County,Liaoning Province in 2019.8%Ningnanmycin AS（aqueous）was dosed at900 g/ha（72g a.i./ha）in the early stage of the onset of ginseng disease,the stems and leaves were sprayed once,and ginseng plants and soil samples were collected at the set interval to determine the residual digestion dynamics of ningnanmycin.The results showed that the degradation dynamics of ningnanmycin conformed to the first order kinetic equation,the half-life of ningnanmycin in ginseng plant was 12.4 d,and the half-life of ningnanmycin in the soil was 3.7～7.3 d,which was a easily degradable pesticide(t_1/2<30 d).3.The final residues of ningnanmycin in fresh ginseng,dried ginseng,ginseng plant and soil were determined.In 2019,the final residue test was conducted in Baishan city of Jilin Province,Fusong city of Jilin Province,Huanren city of Liaoning Province,and Yanji city of Jilin Province.At the test dose of 900 g/ha（72 g a.i./ha）at the initial stage of ginseng disease,the stems and leaves were sprayed for 3 times,the application interval was 7 d,and there were two harvesting intervals of 14 d and 21 d.The final residue of ningnanmycin in fresh ginseng during harvest was less than 0.1 mg/kg,the final residue in dried ginseng was less than 0.2mg/kg,the final residue in ginseng plant was less than 0.1～0.152 mg/kg,the final residue in the soil was less than 0.1～0.132 mg/kg.4.According to the final residual test data in ginseng,the long-term dietary risk of ningnanmycin in ginseng was evaluated,the results showed that the RQ value of ningnanmycin in fresh ginseng was 2.50%,the RQ value of ningnanmycin in dried ginseng was 2.56%,the long-term risk entropy value was less than 100%,which mean that the risk was acceptable.According to the results of determination and analysis,It is suggested that the MRL value of ningnanmycin on fresh ginseng and dried ginseng were 0.2 mg/kg and 0.5 mg/kg,respectively.The recommended dosage of 8%ningnanmycin was 675～900 g/ha（54～72 g a.i./ha）for three times,and the safe interval was 14 days.The residues of ningnanmycin in ginseng during harvest were lower than the recommended MRL value,so it was safe to eat.