Study On Analysis Method Of Pesticide And Its Residues

Two parts are given in thesis, the main results are expressed as follows:1. Electrochemical analysis of pesticideInvestigations had been performed on the determination of carbofuran. In a supportingelectrolyte containing 0.2mol/LNH3-NH4Cl at pH8.8, carbofuran produced a sensitive reduction peak by cyclic voltammetry and linear scanning voltammetry. The peak potential was -1.21V (vs.SCE) . The linear relationship of the peak current and the carbofuran concentration was in the range of 5.0 × 10-6 mol/L to 1.0×10-4 mol/L(r = 0.9995). The relative standard deviation of 5.0×10-5 mol/L carbofuran for 6 parallel determinations was 0.2%. The peak also showed adsorptive characteristics. The mechanism of electrode reduction was discussed. The method had been applied to the determination of biodegradation of carbofuran products with satisfactory result. Degradation percentage of carbofuran was 98% during 96 hours.A new method was developed for determination of tetramethylthiuram disulfide (thiram) based on the formation of thiram- Cu2+ complex by square-wave voltammetry on a glassy carbon electrode. There was a good linear relationship between peak current and concentration of thiram in the range of 6.0 × 10-6 - 8.0 × 10-5 mol/L (r = 0.9986). The method was applied to the determination of thiram residue hi plant with satisfactory results, compared with results achieved by using HPLC. Two oxidation peaks and two reduction peaks were obtained by cyclic voltammetry on a glassy carbon electrode in 0.2 mol/L HAc-NaAc (pH = 4.0) solution containing thiram- Cu2+ complex. The electrode reaction process was quasi-reversible with adsorptive characteristics. The mechanism of electrode reaction and the degradation of thiram promoted by Cu2+ were discussed. The compositionand stability constant of the complex were determined. The amount adsorbed, the rate constant (k) of the electrode reaction and the electrode transfer coefficient (a) were calculated.2. Five pesticides, acetamiprid, imidacloprid, carbofuran, triazophos,primicarb and three sulfonylurea herbicides-chlorsulfuron,metsulfuron methyl and chlorimuron ethyl were separated by MEKC in a 75cm × 50μm uncoated flexible fused silica capillary column (effective length=60cm) with buffer solution consisting of a mixture of 10 mmol/L borate buffer(pH8.0), 54 mmol/L SDS and 4% methanol in water. SDS concentration was examined for getting the best seperation.