Study On Analysis Method Of Pesticide And Its Residues

Two parts are give in the thesis:1. Electrochemical analysis of pesticideThe voltammetric behavior of imidacloprid at a glassy carbon electrode was investigated by square wave voltammetry. In a base solution of 0.2 mol L-1NH3-NH4C1 (pH 9.0) , square wave voltammetry displayed a sensitive reduction peak at -1.24 (vs. Ag/AgCl) . There was a good linear relationship between the peak current and the concentration of imidacloprid from 6.72 10-6 to1.68 10-4 mol L-1, the relative standard deviation of 1.50 10-4 mol L-1 imidacloprid in parallel assays was 2.7%. Imidacloprid also showed adsorptive characteristics at the electrode.The voltammetric behavior of Thiram-Cu (II) complex was studied by single-sweep oscillopolarogaphy. In a medium of HAc-NaAc (pH4.0) buffer solution, a sensitive reduction wave of Thiram-Cu (II) was obtained at -1.06 V (vs. SCE) . The peak current is proportional to the concentration of thiram over the range of 1.25 10~6~3.00 10-5mol L-1. The method has been applied to the determination of residues of thiram in plant and compared with HPLC with satisfactory results. And the degradation of thiram by Cu2+ was also studied by spectrophotometry. Furthermore, its electrode reaction mechanism was proposed in this paper.2. Analysis of pesticide residueThe Capillary gas chromatographic method (GC) was introduced for determining BHC and DDT residues in soil. And three extracted methods, such as Soxhelt Extraction, Mechanical Shaking Extraction (MSB ) and Ultrasonic wave Assistant Extraction (UAE) have been studied. The analytical results showed that the efficiency of USE, MAE was equivalent to that of Soxhelt. For sample of 10 g weight, the detection limit of -BCH, -BCH, - BCH, - BCH, p p' -DDE, o p ' -DDT, p p ' -ODD and p p ' -DDT were 0.0001, 0.0001, 0.0003, 0.0001, 0.0002, 0.0002, 0.0001, 0.0003mg kg-1 respectively.The sample recovery was 67%~ 90 %, and the relative standard deviation was 0.70%-9.5%.Gas chromatography method is widely used to determine the residues of the Organophosphorous pesticides. The organophosphorous pesticides were extracted from vegetable with dichloromethane, separated by capillary column and detected by GC-FPD. The method was proved to be simple, rapid and sensitive. Sample recovery was 50%~ 92 %, and the qautitatve limit of methamidophos, omethoate, phorate, dimethoate and parathion were 0.005 , 0.003, 0.003, 0.002 , 0.002 mg kg-1 respectively.