Residues Determination Of Oxyfluorfen, Prometryn And Chloramphenicol By GC/MS

With the improvement of people’s living standard, food safety has become a hot issue which has attracted great concern of the society. In the risk analysis of food safety, the sources of food pollution mainly include residues of pesticide, veterinary drugs, food additives etc. The most harmful residues can be detected and analyzed by chromatography. Method improvement of sample pre-treatment and apparatus would benefit the detection rapidly and accurately.Herbicide as the largest proportion of pesticide has complex structures. It is imperative to set up a rapid, accurate and multiresidue analytical method to make risk analysis of the new agrochemical. In chapter two of this paper, GC-MS analytical method was presented to detect the residues of herbicide oxyfluorfen and prometryn in garlic and the soil. The samples were extracted by acetone+ethyl acetate, purified through the column of Florisil and analyzed by GC-MS. The result showed that within the concentration of0.01～1.0mg/L, the standard curves of oxyfluorfen and prometryn were good and related coefficients were r=0.998and r=0.997respectively. The LOQ was0.01mg/kg. The recoveries of oxyfluorfen in garlic stem, garlic and soil were86.5%～91.7%,91.6%～104.1%and85.2%～93.1%respectively; the relative standard deviations were3.5%～9.6%,1.8%～3.9%and3.5%～5.0%respectively. The recoveries of prometryn in garlic stem, garlic and soil were89.6%～95.3%,87.3%～100.9%and87.1%～96.4%, RSDs were1.7%～6.0%,2.8%～6.9%and3.1%～8.8%respectively. It has proved that the method can be used to detect oxyfluorfen and prometryn.In chapter three of this paper, the GC-MS method was used to detect samples. The results showed that the degradations of oxyfluorfen and prometryn in soil were in accordance with the first order dynamic equation and the average half-lifes were17.2days and26.4days respectively. The residue of oxyfluorfen and prometryn in garlic stem was too low to count half-life. Oxyfluorfen and prometryn were not detected in garlic stem and garlic and very low in the soil. According to the reference of the international MRL, it was suggested that30%wettable powder of oxyfluorfen and prometryn with dosage of900a.i.g/hm2could be safely used for pre-emergence soil.In chapter four of this paper, the detection method of chloramphenicol (CAP) in marine products by GC-MS was presented, mainly studied the effect of pH. Recovery experiments were done in7different pH values. The samples were extracted by ethyl acetate, removed fat by hexane, purified through C18solid phase extraction column, derivatived by Slilyl reagents and analyzed by GC-MS. The results showed that within0.1～10.0μg/L, the standard linear curve is good, r=0.9996. When pH was5.5～6.7, the LOQ was0.2μg/kg, the recoveries were85.6%～103.2%, RSD was1.0%～6.3%. But when pH was lower than3.2or higher than10.4, the recoveries were too low to detect. So when detect CAP, it’s better to extract CAP in neutral or mildly acidic environment.