Esterase Extracted And Applied To The Study Of The Residues Of Chlorpyrifos

Recently the pesticide is widely used to prevent and cure the plant diseases and insect pests in the agriculture and household. Though it makes the output of crop increase and to a certain extent it protects human beings' health because of the pesticide, especially the organophosphorus pesticide abuse. It brings serious environment pollution and destroys the balance of zoology. Therefore, how to fast and effectively detect the organophosphorus pesticide has a very important signification. Conventional, high sensitive and special methods used to detect residual organophosphorus pesticides include chromatography, mass spectrometry and spectroscopy, et al.. They are all time consuming and costly and are hard to satisfy the increasing requirements of the spot detection. As a comparison, the method of enzyme detection provides a promising way to detect organophosphorus pesticides which is both rapid and simple.Firstly from three aspects of pesticide, esterase and biosensor, this thesis describes the respective development, secondly further certificates the fact that those combinations bring a great transformation in the analysis detection. Those make the convenient, rapid, good selective, high sensitive, low cost methods of detecting pesticides much more popular, much more adapted to the requirements of the spot detection.The method of organophosphorus pesticide enzyme detection can be separated into two kinds, one is the model of hydrolyzation, and the other is the model of inhibition. This thesis mostly aims at the mechanism of active inhibition of enzyme, and develops a number of primary study of the plant esterase and pig liver esterase that attribute to the B-esterase to detect organophosphorus pesticide. Chlorpyrifos, a widely used moderate toxic organophosphorus pesticide nowadays in China, is chosen as the subject investigated.Plant esterase and pig liver esterase can hydrolyze acetyl-2.6,-Dichloroindophen-ol which causes the change of absorbance. This characteristic is used to detect the Chlorpyrifos in this article. The orthogonal test is designed to find optimal operating conditions of the plant esterase and these conditions effectively reduce the detection limit. Using the matlab programs process the data that are attained from the experiments to get a standard curve of Chlorpyrifos residue. This provides an effective method todetect Chlorpyrifos residue. Under this optimal condition the half ration detection concentration range of Chlorpyrifos is 0.05 mg/L~0.09mg/L. If the plant esterase is further purfied through chromatography on CM-cellulose, using this enzyme carries through analysis, it can be found that the limit detection of Chlorpyrifos will be further reduced. At the same time, using pig liver esterase that is primarily purified through chromatography on DEAE-cellulose also can detect the Chlorpyrifos residue. Based on active inhibition method of pig liver esterase the half ration detection limit range of Chlorpyrifos is 0.56mg/L~64.31mg/L. From this contrast, the detection limit of plant esterase is much lower than that of pig liver esterase, but the concentration range of the latter is much wider than the former. Both of these methods have the merits of convenient operation, high sensitisation and low cost. They are very adapted to the fast qualitative detection on the spot and the half ration detection on detection institution.