| During 4 or 6 years growth period,garden ginseng(cultivated Panax ginseng C.A.Mey.),which may be affected by more than 40 kinds of diseases and insect pests, commonly used chemical pesticides to prevent and control, effectively protect yield of Panax ginseng. Quintozene, Chlorpyrifos, Procymidone was commonly used to prevent and control Rhizoctonia solani Kuhn, Pythium debaryanum Hesse, Botrytis cinerea Pers and Alternaria panax Whetz. As a result of the inherent nature of pesticide, irregulate use of pesticide and environmental factors,casuing Quintozene,chlorpyrifos, procymidone residues affected Panax ginseng products quality security.3 kinds of pesticides were selected,which were applied on practical dosage in Panax ginseng fields, to study the degradation dynamics of pesticides and to assess the dietary risk assessment of Panax ginseng roots of the first growing season.1.A method for the determination of residues of Quintozene, Chlorpyrifos and Procymidone and their derivatives in soil,Panax ginseng roots, stems and leaves of Panax ginseng by gas chromatography tandem mass spectrometry(GC-MS/MS) was established. All samples were extracted by acetonitrile.Soil sampls were purified by Florisil solid phase extraction column,and Panax ginseng root samples purified by Graphite amino solid phase extraction column, which were identified by Multi Rection Monitor(MRM)mode and quantified by external standard method. The calibration curves of 3 kinds of pesticides and their derivatives were linear in the range of 0.01μg/m L ~ 1μg/m L,relative standard deviation ranged from 0.9878 to1.000.The detection limit(LOD) was 0.00005 ~ 0.0003 mg/kg, limit of quantification(LOQ) was 0.0002 ~ 0.0009 mg/kg.At three addition levels of 0.05,0.1,0.2 mg/kg, the average recoveries ranged from 81% to 110%,with the relative standard deviation ranged from 1.3% to 10.7%.Average recoveries were between 70% to 110%,Relative standard deviation was less than 15%,indicating established method was suitable for the detection of residues of 3 pesticides and their derivatives in soil, Panax ginseng roots and stems and leaves of Panax ginseng.2.A field test scheme of 3 pesticides was developed.Degradation dynamics of experimental results :Quintozene was applied on soil one time in the dosage of 80000 g a.i. / hm2,half life was 27.50 d.Chlorpyrifos was applied on soil one time in the dosage of 20000 g a.i. / hm2,half life was 20.26 d.Procymidone was applied on Panax ginseng leaves one time in the dosage of 1400 g a.i. /hm2,half life was 18.28 d.Quintozene was applied on soil one time in the dosage of 80000 g a.i. /hm2,the average residual amount in soil was 4.9887 mg/kg,in Panax ginseng roots was 10.3502 mg/kg,respectively.Quintozene migrated from soil to Panax ginseng roots,migration ratio was 48.19%,the average residue in stems and leaves of Panax ginseng of Quintozene was2.3622 mg/kg,Quintozene migrated from Panax ginseng roots to stems and leaves,migration ratio was 22.82%.Chlorpyrifos was applied on soil one time in the dosage of 20000 g a.i. /hm2,the average residual amount in soil was 0.3107 mg/kg,in Panax ginseng roots was 0.2317 mg/kg,respectively.Chlorpyrifos migrated from soil to Panax ginseng roots,migration ratio was 74.57%,the average residue in stems and leaves of Panax ginseng of Chlorpyrifos was 0.0812 mg/kg, Chlorpyrifos migrated from Panax ginseng roots to stems and leaves,migration ratio was 35.04%.Procymidone was applied on Panax ginseng leaves one time in the dosage of 1400 g a.i. /hm2,in 109 d,the average residue in stems and leaves of Panax ginseng was 0.4220 mg/kg,in Panax ginseng roots was 0.0475 mg/kg,respectively.Procymidone migrated from stems and leaves of Panax ginseng to Panax ginseng roots,migration ratio was 11.25%,Procymidone migrated from Panax ginseng roots to soil,migration ratio was 4.42%.3.For Quintozene, Chlorpyrifos and Procymidone,their chronic dietary risk expressed as %ADI was 3356%,64%,19%,respectively. %ADI which was less than 100% was assumed acceptable :%ADI of Chlorpyrifos or Procymidone was less than or equal to 100%,so the dietary risk was very low. %ADI which was more than 100% was unacceptable : %ADI of Quintozene was more than 100%, constituting a dietary risk in Panax ginseng root. For Panax ginseng belongs to a perennial herb, final residue of Quintozene in Panax ginseng roots during other growing seasons or harvest time is unknown, the chronic dietary risk of Panax ginseng root should be studied further. Chlorpyrifos possesses acute toxicity,According to the acute reference dose(ARf D) of chlorpyrifos formulated by JMPR,calculating short-term dietary intake risk as %ARf D of Chlorpyrifos in Panax ginseng root(4.266%),%ARf D is less than or equal to 100%, short-term dietary risk of Panax ginseng root is low,which is acceptable. Quintozene and procymidone does not exist acute toxicity, therefore can not be short-term dietary risk assessment. |
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