| As one of the leading agricultural producers, the production of pesticide in ourcountry ranks second in the world. The pesticide, which guaranteed the the cropproduction, can certainly bring huge economic benefit to our agriculture industry, butit also leads to serious pollution to the agricultural product and also the environment.So in order to make people have a more healthy life, we must strengthen the analysisand determination of pesticide residue s in agricultural products and environment.Traditional detection methods of the pesticide residu es include gaschromatography, liquid chromatography, mass spectrometry and so on. In recent years,electrochemical method s and fluorescen t method s are well developed. Comparied withthe expensive, reagent and time consuming and off-line traditional methods,electrochemical method s and fluorescen t method s have attracted much attention due totheir high sensitivity, simple operation, low reagent consumption and low cost.Therefore, in this article we mainly design several electrochemical sensor s andfluorescent probe method s to achieve the purpose of the pesticide detection.The main content of this paper includes the three following sections:(1) Phenothri n is an important insecticidal and acaricidal agent with certaintoxicity. It is highly necessary to develop a rapid, sensitive and selective method forphenothri n assay. The thermal initiation method is used to prepare molecularlyimprinted electrochemical sensor, which selects phenothri n as imprinted molecule.Some factors which affect the preparation of the molecular ly imprint edelectrochemical sensor are optimized and its sensing performance is evaluated. Thesensor exhibits a highly sensitivity and selectivity towards phenothri n.The responsecurrent depend s on the concentration of phenothrin at the range of1.0~100.0μmol/Land the linear equation is Δi (μA)=0.0418x+2.270(r=0.9958), the detection limit is2.0×10-7mol/L. The sensor has been applied to analysis of phenothri n in the water ofXiangjiang River with a satisfactory recovery rates ranging from95.62%to103.19%,showing a great potential for the phenothri n assay.(Chapter2)(2) A novel, fast and sensitive electrochemical biosensor based onbiometallization and silver-enhancing for continuous signal amplification is describedfor the detection of organophosphate pesticide (OP). Malathion is used as a model toconfirm our strategy. In this method, the immobilized AChE mediate s the hydrolysis of ATCl and yield a reducing agent thiocholine which reduce s AuCl4-to form goldnanopart icles (AuNPs). The electrode is immersed in the silver enhancer solution of1.0mol/L NH3/2.0×103mol/L AgNO3, and under the condition of-0.10V asdeposition potential, the silver is only deposited on the surface of AuNPs instead of theelectrode surface for continuous signal amplification. The deposited silver is thenquantified by linear sweep voltammetry (LSV). In the presence of malathion, thedecrease in the stripping peak currents of silver is proportional to the concentration ofmalathion from0.1μg/L to1000μg/L, and the linear equation is ipa=149.9–40.49lgC(r=0.9963), The detection limit is found to be as low as0.05μg/L. The utilization ofbiometallization and silver-enhanced for continuous signal amplification to detect OPdramatically enhance the sensitivity of AChE electrochemical biosensors. The sensorhas been applied to analysis of OP in the water of the Xiangjiang River with asatisfactory recovery rates ranging from95.49%to102.2%, showing a great potentialfor the OP assay.(Chapter3)(3) A fluorescent probe method for the organophosphorus pesticide is developed.In this method, the fluorescence intensity of thioflavin T (ThT) obviously increases inthe presence of a certain concentration of hexadecyl trimethyl ammonium bromide(CTMAB), and the enhanced fluorescence intensity is declined dramatically with theaddition of organophosphorus pesticide in the ThT-CTMAB system. The results showthat the change of fluorescence intensity is proportional to the concentration oforganophosphorus pesticides. The linear range is0.025~0.5mg/L, the linear equationis F=615.0–350.4C, and the detection limit reaches0.015mg/L. The method hasbeen applied to the determination of the organophosphorus pesticide residues in applesamples with a satisfactory recovery rates ranging from94.10%to103.7%, whichresult is satisfactory.(Chapter4)... |
PDF Full Text Request