The Study Of Multi-class Pesticide Residues Analytical Technology And Applications In Ginseng

Mass spectrometry （MS） is becoming an indispensable technique in food andenvironmental studies. In the research, gas chromatography mass （GC-MS） and liquidchromatography mass （LC-MS） were used to study the fate of pesticide residues in ginsengand environmental samples. Target analytes relevant to human and environmental health wereselected in the studies, which include19trace organochlorinated pesticides,9strobilurinfungicides and8commonly used pesticides in ginseng.A new gas chromatographic-mass spectrometry method was developed for simultaneousmeasurement of19trace organochlorinated pesticide residues in ginseng. The ginsengsamples were extracted by acetonitrile, and the extracts were cleaned up with a column of6mL Florisil by solid phase extraction. The19organochlorinated pesticides were separatedthrough DB^-17MS capillary column and were measured by GC-MS. The recoveries rateranged from70.0%to117.0%. When0.05².00mg/kg pesticides were added, the relativestandard deviations of detections were ranged from1.4%to19.7%, and the limit ofdetermination was lowered to0.010⁰.040mg/kg. This method is rapid, sensitive and suitablefor the analysis of organochlorinated pesticide residues in ginseng.A sensitive and selective method was developed for the determination of residuesincluding azoxystrobin, dimoxystrobin, fluoxastrobin, kresoxim-methyl, e-metominostrobin,picoxystrobin, mepanipyrim, pyraclostrobin and trifloxystrobin in panax. The extract wascleaned up by solid-phase extraction （SPE）, and the elute solution was evaporated andresoluted in a definite volume. Determination and confirmation were made by gaschromatography-mass spectrometry at selective ions monitoring mode with external standardmethod. The average recoveries spiked samples at the three concentrations of0.025,0.25,2.0mg/kg ranged from79.9%to106.7%with relative standard deviation ranged from0.5%to12.1%. The limits of detection were0.01⁰.025mg/kg in variesou matrixes.QuEChERS methods for the determination of8pesticides in ginseng by highperformance liquid chromatograpy electrospray tandem mass spectromtry （HPLC-MS/MS） inthe mode of MRM were described. The recoveries were ranged from85.9%to102.5%withrelative standard deviation （RSD）<15%. The calibration curve linear with coefficient rangedfrom5ng/mL to250ng/mL, in the concentration level of0.01mg/kg、0.05mg/kg、0.5mg/kg,the LOQ for detection for the8pesticides were ranged from0.1μg/kg to10μg/kg. In thisstudy, matrix effect of8pesticides in ginseng was evaluated. Results indicated that matrixenhancement effects were showed in the most of the pesticides in some extent. In the whole, the developed methods are quick, simple and environment-friendly.To evaluate the risk of pesticide residues, the analytical gas Chromatography-massmethod for determine residues of azoxystrobin and kresoxim-methyl in ginseng and soils wasdeveloped, and the dynamics in ginseng and environment were studied in this paper.The limit of detection of azoxystrobin by GC-MS was1×10^-12g. The limit ofquantification of azoxystrobin by GC-μ-ECD was0.01mg·kg^-1, the recoveries of the methodwere98.2^-103.2%,99.6^-102.8%and100.2^-101.9%in soil, plant and ginseng.The limit of detection of kresoxim-methyl by GC-MS was1×10^-12g, the limit ofquantification of kresoxim-methyl by GC-MS was0.05mg·kg^-1, the recoveries of the methodwere92.2^-100.3%,90.5-94.8%and91.9^-100.3%respectively in soil, plant and ginseng.The residues dynamics of these pesticides in ginseng and soil were studied. The dynamicequations and half-lives were obtained. Suggestions about safety application of thesepesticides and the MRL of these pesticides in ginseng were put forward based on the results.From2008to2011, a series of GAP field trails, in different dose, different applicationtimes, and different harvest intervals time, were carried out in JiLin and BeiJing on twopesticides. The results showed that the original residue level of azoxystrobin andkresoxim-methyl were10.835⁴3.953mg/kg and2.489³.245mg/kg respectively in ginsengplant; the half-lives were0.7².0days and6.9¹5.1days respectively. They are all easy to bedegradated, and after30days,65%of the pesticides were degradated. In the soil, thehalf-lives were2.5³.2days and8.8¹4.3days respectively. The residue of azoxystrobin inginseng is influenced by the interval time directly, but kresoxim-methyl is influenced by theinterval dose. According to Korea guidance, the residue of azoxystrobin and kresoxim-methylare following the limit requirement after applying the azoxystrobin and kresoxim-methyl for3days. So the safety interval is3days.