| Residue of pesticides found in agriculture products, drinking water and environmental exposure has raised much concern from the general public in recent years. In order to protect persons' healthy, the maximum residue levels (MRL) in food were constituted by WHO/FAO-CAC. The constitution as:《Maximum Residue Limits of metalaxyl, procymidone, vinclozolin, thiram, thiophanate-methyl, paraquat, simazine, atrazine and ethephon in apple, pear》on it regulated the MRL of thiram in apple, pear is 5 mg'kg-1 (G/SPS/N/CHN/88); USA allowed the MRL of thiram in apple is 7 mg'kg-1, Europe Union allowed the MRL of thiram in pome is 3 mg·kg-1, Danmark taboo, Japan regulated the MRL of thiram in water should not exceed 0.006 mg·L-1. It is important to exploit simply, fast, efficient pre-treatment technologies for samples and high sensitive, high selective multi-pesticide detections technologies based on pesticide and veterinary drug residues in food and the requirement for international trade on food.The thesis includes two parts:In chapterâ… : Electrochemical analysis of thiramA novel method of the determination of thiram was proposed based on its polarographic catalytic wave in the presence of persulfate. In 0.2 mol·L-1 C4H6O6-C4H4O6KNa (pH=5.5) -1.5×10-3 mol·L-1 K2S2O8 base solution, the peak potential of the polarographic catalytic wave was at -0.5 V (vs. SCE), and the 2nd-order derivative peak current of the catalytic wave was linearly proportional to the thiram concentration in the range of 5.0×10-8-3.0×10-6 mol·L-1. The detection limit was 1.0×10-8 mol·L-1. The relative standard deviations was 1.27% (n=10). The sensitivity of the catalytic wave of thiram was 25 times higher than that of the corresponding reduction wave. The recovery was between 90.29%-96.10% in detection samples. The method was sensitive, simple, rapid. In chapterâ…¡: Electrochemical analysis of thiram-Cu2+The method of the determination of thiram-Cu2+ was proposed based on its polarographic catalytic wave in the presence of persulfate. In 0.2 mol·L-1 C4H6O6-C4H4O6KNa (pH=5.5)-3.0×10-3 mol·L-1 K2S2O8-4.0×10-6 mol·L-1 Cu2+ base solution, the peak potential of the polarographic catalytic wave was at -0.8 V(vs.SCE), and the 2nd-order derivative peak current of the catalytic wave was linearly proportional to the thiram concentration in the range of 1.0×10-8-1.0×10-6 mol·L-1(r=0.999 4). The detection limit was 2.0×10-9 mol·L-1(the detection limit was depreeed 1.9×10-9 mol·L-1). The relative standard deviations was 2.75% (n=10). The sensitivity of the catalytic wave of thiram was 125 times higher than that of the corresponding reduction wave. Use the SPE concentration the sample enrichment time is 10, the recovery was between 83.81%-91.41% in detection samples. The method was sensitive, simple, rapid. |
PDF Full Text Request