Detection Of Various Pesticide Residues In Fruits Using Modified QuEChERS Method With GC-MS/MS

Traditional Chinese medicine and Chinese medicinal materials are one of the most precious quintessences of our country.China is not only the largest market for consumption of Chinese medicinal materials,but also the largest producer of Chinese medicinal materials.Chinese herbal medicines generally have a long planting period,especially root medicines such as Panax quinquefolium,which are more vulnerable to the pollution of pesticide residues.Therefore,it is necessary to establish a rapid detection technology for pesticide residues in Panax quinquefolium.This study combines magnetic nanoparticles with QuEChERS technology,eliminating the complex operation steps such as filtration and centrifugation,not only the purification efficiency will be greatly improved,but also the pretreatment time will be greatly shortened and the operation process will be simplified.Based on the characteristics of magnetic iron tetroxide nanoparticles and combined with gas chromatography-tandem mass spectrometry(GC-MS/MS),an improved QuEChERS pretreatment method was developed for the determination of 121 pesticide residues in Panax quinquefolium.The main research contents and related conclusions of this experiment are as follows:1.Using Panax quinquefolium as raw material,12 representative target pesticides were selected to optimize the extraction and purification conditions,and magnetic ferric oxide nanoparticles were added to the pretreatment step,which improved the traditional QuEChERS pretreatment method.The magnetic ferric oxide nanoparticles were prepared by coprecipitation and characterized by transmission microscopy(TEM).The samples were first extracted with 1% acetic acid-acetonitrile extract,then centrifuged with sodium chloride and anhydrous magnesium sulfate salting out.Finally,the extract was purified with N-propyl ethylenediamine(PSA),graphitized carbon black(GCB)and magnetic ferric oxide nanoparticles(MNPs).2.According to the physical and chemical properties of pesticides,the most suitable parameters of testing equipment for various pesticides were determined,and the optimum parameters of 121 pesticides were established.A method for the determination of 121 pesticide residues in American ginseng was established.Under the optimum conditions,121 pesticides can be separated and characterized well,the linear range is 0.05-100.00 ug/kg,the linear correlation coefficient(R2)of most target pesticides is more than 0.995,the detection limit(LOD)of the method is 0.15-1.50 ug/kg,and the quantitative limit(LOQ)of the method is 0.50-5.00 ug/kg.3.A method for the determination of 121 pesticides in Panax quinquefolium L.and the instrument parameters of gas chromatography-tandem mass spectrometry(GC-MS)were successfully established and applied to the multi-pesticide residue screening of practical samples.The recoveries of 121 target pesticides at 0.50 ug/kg,5.00 ug/kg and 50.00 ug/kg levels ranged from 76.48% to 107.21%,and the relative standard deviation was less than7.62%,which met the requirements of multi-pesticide residue detection.4.80 kinds of American ginseng were randomly sampled from supermarkets and pharmacies in Shandong Province for pesticide residue detection.The results showed that 27 samples of Panax quinquefolium were found to be pesticide residues,but the content of pesticide residues did not exceed the standard.The results also showed that the safety of pesticide residues in Panax quinquefolium was satisfactory,and no highly toxic pesticide residues in Panax quinquefolium which were banned by any country were detected.The method is simple,rapid,sensitive and reproducible.It is suitable for the dete rmination of 121 pesticide residues in Panax quinquefolium L.and has good practical application.