Study On Qualitative And Quantitative Analysis Technology For Herbicide Residues In Soybean

The study was based on the 10th five-year plan Food Safety Key Project "Establishment of systematic determination and rapid screening methods of pesticides and veterinary drugs residues"(2001BA804All) and "Study on pesticides residues determination technology" (2001BA804A17).The study was aimed at filling the blank of herbicides residues determination technology and meeting the international requirement of more and more stringent MRLs.Our paper summarized the development and application history,trend in recent years and generalization of 18 kinds widely used pesticides.The physical and chemical properties and toxicological research were also introduced.This chapter also reviewed the change of pesticides MRLs values,especially the huge change in recent years.For example,the MRLs of the pesticides used in soybeans involved in Japan "positive list" were reviewed.The influence of the MRLs change and lack of determination technology on the soybean consumption and export was also analyzed.The chapter emphasized on the situation of analytical methods of pesticides residues in soybean in China and abroad.In addition,the prohibited pesticides regulated in developed countries and some limitation standards on soybean in our country were also analyzed in the chapter.The toxicology and analytical methods of pesticides metabolites arisen recently in foreign countries were also reviewed.The establishment of systematic determination technology was put forward to meet the requirement of pesticides MRLs.According to the pesticides classification,the determination methods of dinitroaniline, phenoxycarboxylic acids,sulfonyluerea,amides,triazines residues were demonstrated to meet the different requirements.Dinitroaniline herbicides were soluble in organic solvent and there were electronegative atoms in molecules,therefore,GC/ECD method which showed great sensitivity and selectivity was chosen and the parameters of GC-MS for confirmative determination was established.Phenoxycarboxylic acids herbicides belong to organic acid herbicides and were easily dissolved in water.To get the formate products,boron trifluoride-ether-methanol was used for derivation.Then the GC-MS method was established for both qualitative and quantitative analysis and the sensitivity of method was up to 0.005 mg/kg.The baseline separation and HPLC quantitative determination of sulfonyluerea herbicides were achieved using phosphate buffer/acetonitrile gradient elution and the method was reliable.In this part,the satisfactory detection limits and resolution were obtained under the optimal extraction conditions.Acetonitrile/ water were used as mobile phase and the wavelength was set at 210 nm.The mixture of triazine herbicides were well separated using HPLC/DAD method,the experimental conditions were acetonitrile/water gradient elution and 228 nm.The ultra performance analytical method based on 1.7μm particles was established. Compared with HPLC,UPLC^TM has higher column efficiency and the separation could be achieved under higher flow rate and back pressure.UPLC/MS/MS method was used for the determination of 14 different kinds herbicides commonly used in agriculture,totally 111 compounds were extracted,purified and separated,the excellent results were obtained.The sensitivity of the method was up to 0.1 mg/kg.HPLC-TOF-MS method was used for the screening and determination of unknown herbicides residues in soybean for the first time.TOF-MS could provide the accurate molecular weight for the suspicious herbicide residues,therefore,the screening and confirmation of the unknown targeted herbicide residues could be achieved.The establishment of the method solved the key problem of the screening technology of totally unknown samples and provided the technical support for the national farm produce residues monitoring and spot test.