| The matrix solid-phase disperser is a new sample preparation technique developed in recent years, it reveals unique characteristic duering processes the solid, the semi-solid or coherent liquid sample, this method is applied in the modern pesticide residue analysis more and more widely. The MSPD-GC/MS method for simultaneous determination of 37 pesticides in vegetable samples was developed and evaluated which is fast, effective, with high efficency, and conforms to the agriculture analysis requirement. This paper particularly introduced the progress in the MSPD technology, MSPD principle and each influent factor to MSPD technology, optimized the MSPD condition, and used it in the study on residue dynamic of pesticides. The residue dymanics and final residues of chlorpyrifos and cypermethrin were studied through the field experiment, and the scientific basis for the handling of agricultural chemicals safety standard formulation was provided. Primarily study result as follows:1. Many sample preparation methods were redeeply studied and carefully compared in this experment.The principal of MSPD was discussed profoundly and factors which can influence the MSPD were redesigned elaborately to the best state: selected the C18 as sorbent, the best rate of sample and sorbent is 1∶2,with ethyl acetate as elution,the dose was 20mL.2. The MSPD preparation method was developed for rapid determining 37 pesticides in 4 vegetables. Pesticides were extracted and dispersed by C18 with ethyl acetate as eluent, fast sceening, definite quantiting and confirming by GC-MS. Recovery experiment was carried out, when added 0.1～0.5 mg/kg 37 pesticides, the control group was set and the external standard method was used as well. Good linear and lower limits of detection were obtained. The recovery range of 37 pesticides in tomato was between 86.5%～113.5%, RSD was lower than 21%; the recovery range of 37 pesticides in cucumber was between 84.9 %～115.7%, RSD was between 1.3%～18.9%; the recovery range in pepper was between 80.3%～106.5%,RSD was lower than 17%, except vinclozolin was 23.5%; the recovery range of in spinach was between 82.9%～110.4%, RSD was lower than 13%, except vinclozolin was 22.7%.3. The residual dynamics and final residues of chlorpyrifos in tomato, cucumber, spinach and pepper grown in greenhouse were studied through field experiment and MSPD-GC/MS analysis. The results showed that when high dosage 720g ai/ha water solution of 48% chlorpyrifos was applied in 4 vegetable for one time, the primitive residues amount of chlorpyrifos in 4 vegetable were 5.36 mg/kg, 5.82 mg/kg, 4.35 mg/kg and 6.74 mg/kg respectively, the half-life of chlorpyrifos in 4 vegetables was 0.96d, 0.91d, 1.28d and 1.43d; after 16.2d, 15.7d, 18.3d and 19.5d, the degradation rate in 4 vegetables was more than 99%, the degradation process of chlorpyrifos was fitted the first-order kinetic equation.4. Study on the residual dynamics and final residues of cypermethrin in tomato, cucumber, pepper,and spinach grown in greenhouse were carried out. The results showed that when high dosage 720g ai/ha water solution of 4.5% cypermethrin was applied in 4 vegetable for one time, the primitive residues amount of cypermethrin in 4 vegetables was 7.47 mg/kg, 7.97 mg/kg, 6.93mg/kg and 9.26 mg/kg respectively, the half-life of cypermethrin in 4 vegetable was 3.23d, 3.06d, 2.74d and 4.85d; after 30.7d, 31.4d, 28.2d, and 35.9d, the degradation rate in 4 vegetables was more than 99%, the degradation process of cypermethrin was fitted the first-order kinetic equation. . |
PDF Full Text Request